diff --git a/app/logical/related_tag_calculator.rb b/app/logical/related_tag_calculator.rb
new file mode 100644
index 000000000..94b0a237f
--- /dev/null
+++ b/app/logical/related_tag_calculator.rb
@@ -0,0 +1,33 @@
+class RelatedTagCalculator
+  def find_tags(tag, limit)
+    ActiveRecord::Base.connection.select_values_sql("SELECT tag_string FROM posts WHERE tag_index @@ to_tsquery('danbooru', ?) ORDER BY id DESC LIMIT ?", tag, limit)
+  end
+  
+  def calculate_from_sample(name, limit, category_constraint = nil)
+    counts = Hash.new {|h, k| h[k] = 0}
+    
+    find_tags(name, limit).each do |post|
+      if category_constraint
+        categories = Tag.categories_for(post.tag_array)
+        
+        post.tag_array.each do |tag|
+          if categories[tag] == category_constraint && tag != name
+            counts[tag] += 1
+          end
+        end
+      else
+        post.tag_array.each do |tag|
+          if tag != name
+            counts[tag] += 1
+          end
+        end
+      end
+    end
+    
+    counts
+  end
+  
+  def convert_hash_to_string(hash)
+    hash.to_a.sort_by {|x| -x[1]}.flatten.join(" ")
+  end
+end
diff --git a/app/models/job.rb b/app/models/job.rb
new file mode 100644
index 000000000..df6f1896c
--- /dev/null
+++ b/app/models/job.rb
@@ -0,0 +1,188 @@
+class Job < ActiveRecord::Base
+  CATEGORIES = %w(mass_tag_edit approve_tag_alias approve_tag_implication calculate_tag_subscriptions calculate_related_tags calculate_post_count calculate_uploaded_tags s3_backup)
+  STATUSES = %w(pending processing finished error)
+  
+  validates_inclusion_of :category, :in => CATEGORIES
+  validates_inclusion_of :status, :in => STATUSES
+  
+  def data
+    JSON.parse(data_as_json)
+  end
+  
+  def data=(text)
+    self.data_as_json = text.to_json
+  end
+  
+  def execute!
+    if repeat_count > 0
+      count = repeat_count - 1
+    else
+      count = repeat_count
+    end
+    
+    begin
+      execute_sql("SET statement_timeout = 0")
+      update_attribute(:status, "processing")
+      __send__("execute_#{task_type}")
+      
+      if count == 0
+        update_attribute(:status, "finished")
+      else
+        update_attributes(:status => "pending", :repeat_count => count)
+      end
+    rescue SystemExit => x
+      update_attribute(:status, "pending")
+    rescue Exception => x
+      update_attributes(:status => "error", :status_message => "#{x.class}: #{x}")
+    end
+  end
+  
+  def execute_mass_tag_edit
+    start_tags = data["start_tags"]
+    result_tags = data["result_tags"]
+    updater_id = data["updater_id"]
+    updater_ip_addr = data["updater_ip_addr"]
+    Tag.mass_edit(start_tags, result_tags, updater_id, updater_ip_addr)
+  end
+  
+  def execute_approve_tag_alias
+    ta = TagAlias.find(data["id"])
+    updater_id = data["updater_id"]
+    updater_ip_addr = data["updater_ip_addr"]
+    ta.approve(updater_id, updater_ip_addr)
+  end
+  
+  def execute_approve_tag_implication
+    ti = TagImplication.find(data["id"])
+    updater_id = data["updater_id"]
+    updater_ip_addr = data["updater_ip_addr"]
+    ti.approve(updater_id, updater_ip_addr)
+  end
+  
+  def execute_calculate_tag_subscriptions
+    last_run = Time.parse(data["last_run"])
+    if last_run.nil? || last_run < 20.minutes.ago
+      TagSubscription.process_all
+      update_attributes(:data => {:last_run => Time.now.strftime("%Y-%m-%d %H:%M")})
+    end
+  end
+  
+  def execute_calculate_related_tags
+    tag_id = data["id"].to_i
+    tag = Tag.find_by_id(tag_id)
+    if tag
+      tag.commit_related(Tag.calculate_related(tag.name))      
+    end
+  end
+  
+  def execute_calculate_post_count
+    Tag.recalculate_post_count(data["tag_name"])
+  end
+  
+  def execute_calculate_uploaded_tags
+    tags = []
+    user = User.find(data["id"])
+    CONFIG["tag_types"].values.uniq.each do |tag_type|
+      tags += user.calculate_uploaded_tags(tag_type)
+    end
+    
+    user.update_attribute(:uploaded_tags, tags.join("\n"))
+  end
+  
+  def execute_bandwidth_throttle
+    bw = File.read("/proc/net/dev").split(/\n/).grep(/eth1/).first.scan(/\S+/)[8].to_i
+    if $danbooru_bandwidth_previous
+      diff = bw - $danbooru_bandwidth_previous
+    else
+      diff = 0
+    end
+    $danbooru_bandwidth_previous = bw
+    Cache.put("db-bw", diff)
+  end
+  
+  def execute_s3_backup
+    last_id = data["last_id"].to_i
+    
+    begin
+      Post.find(:all, :conditions => ["id > ?", last_id], :limit => 200, :order => "id").each do |post|
+        AWS::S3::Base.establish_connection!(:access_key_id => CONFIG["amazon_s3_access_key_id"], :secret_access_key => CONFIG["amazon_s3_secret_access_key"])
+        if File.exists?(post.file_path)
+          base64_md5 = Base64.encode64(Digest::MD5.digest(File.read(post.file_path)))
+          AWS::S3::S3Object.store(post.file_name, open(post.file_path, "rb"), CONFIG["amazon_s3_bucket_name"], "Content-MD5" => base64_md5)
+        end
+
+        if post.image? && File.exists?(post.preview_path)
+          AWS::S3::S3Object.store("preview/#{post.md5}.jpg", open(post.preview_path, "rb"), CONFIG["amazon_s3_bucket_name"])
+        end
+
+        if File.exists?(post.sample_path)
+          AWS::S3::S3Object.store("sample/" + CONFIG["sample_filename_prefix"] + "#{post.md5}.jpg", open(post.sample_path, "rb"), CONFIG["amazon_s3_bucket_name"])
+        end
+      
+        update_attributes(:data => {:last_id => post.id})
+        base64_md5 = nil
+      end
+
+    rescue Exception => x
+      # probably some network error, retry next time
+    end
+  end
+  
+  def pretty_data
+    begin
+      case task_type
+      when "mass_tag_edit"
+        start = data["start_tags"]
+        result = data["result_tags"]
+        user = User.find_name(data["updater_id"])      
+        "start:#{start} result:#{result} user:#{user}"
+    
+      when "approve_tag_alias"
+        ta = TagAlias.find(data["id"])
+        "start:#{ta.name} result:#{ta.alias_name}"
+    
+      when "approve_tag_implication"
+        ti = TagImplication.find(data["id"])
+        "start:#{ti.predicate.name} result:#{ti.consequent.name}"
+    
+      when "calculate_tag_subscriptions"
+        last_run = data["last_run"]
+        "last run:#{last_run}"
+
+      when "calculate_related_tags"
+        tag = Tag.find_by_id(data["id"])
+        if tag
+          "tag:#{tag.name}"
+        else
+          "tag:UNKNOWN"
+        end
+    
+      when "calculate_post_count"
+        "tag:" + data["tag_name"]
+        
+      when "calculate_uploaded_tags"
+        "user:" + User.name(data["id"])
+        
+      when "bandwidth_throttle"
+        ""
+        
+      when "s3_backup"
+        "last_id:" + data["last_id"].to_s
+        
+      end
+    rescue Exception
+      "ERROR"
+    end
+  end
+  
+  def self.pending_count(task_type)
+    JobTask.count(:conditions => ["task_type = ? and status = 'pending'", task_type])
+  end
+  
+  def self.execute_once
+    find(:all, :conditions => ["status = ?", "pending"], :order => "id desc").each do |task|
+      task.execute!
+      sleep 1
+    end
+  end
+end
diff --git a/app/models/post.rb b/app/models/post.rb
index 34b365888..5a44d639c 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -11,6 +11,7 @@ class Post < ActiveRecord::Base
   belongs_to :updater, :class_name => "User"
   has_one :unapproval, :dependent => :destroy
   has_one :upload, :dependent => :destroy
+  has_one :moderation_detail, :class_name => "PostModerationDetail", :dependent => :destroy
   has_many :versions, :class_name => "PostVersion", :dependent => :destroy  
   has_many :votes, :class_name => "PostVote", :dependent => :destroy
   attr_accessible :source, :rating, :tag_string, :old_tag_string, :updater_id, :updater_ip_addr
diff --git a/app/models/post_moderation_detail.rb b/app/models/post_moderation_detail.rb
new file mode 100644
index 000000000..0f001287c
--- /dev/null
+++ b/app/models/post_moderation_detail.rb
@@ -0,0 +1,19 @@
+class PostModerationDetail < ActiveRecord::Base
+  belongs_to :post
+  belongs_to :user
+  
+  def self.filter(posts, user, select_hidden = false)
+    hidden = where(:user_id => user.id).select("post_id").map(&:post_id)
+    if select_hidden
+      posts.select {|x| hidden.include?(x.id)}
+    else
+      posts.reject {|x| hidden.include?(x.id)}
+    end
+  end
+  
+  def self.prune!
+    joins(:post).where("posts.is_pending = FALSE AND posts.is_flagged = FALSE").each do |hidden_post|
+      hidden_post.destroy
+    end
+  end
+end
diff --git a/app/models/tag.rb b/app/models/tag.rb
index 5751cc7fe..62a05fded 100644
--- a/app/models/tag.rb
+++ b/app/models/tag.rb
@@ -305,6 +305,35 @@ class Tag < ActiveRecord::Base
     end
   end
   
+  module RelationMethods
+    def update_related
+      calculator = RelatedTagCalculator.new
+      counts = calculator.calculate_from_sample(Danbooru.config.post_sample_size, name)
+      self.related_tags = calculator.convert_hash_to_string(counts)
+    end
+    
+    def update_related_if_outdated
+      updated_related if should_update_related?
+    end
+    
+    def related_cache_expiry
+      base = Math.sqrt(post_count)
+      if base > 24
+        24
+      else
+        base
+      end
+    end
+    
+    def should_update_related?
+      related_tags.blank? || related_tags_updated_at < related_cache_expiry.hours.ago
+    end
+    
+    def related_tag_array
+      related_tags.split(/ /).in_groups_of(2)
+    end
+  end
+  
   extend ViewCountMethods
   include CategoryMethods
   extend StatisticsMethods
diff --git a/db/development_structure.sql b/db/development_structure.sql
index 352a12a03..d9f3b0a67 100644
--- a/db/development_structure.sql
+++ b/db/development_structure.sql
@@ -762,6 +762,41 @@ CREATE SEQUENCE forum_topics_id_seq
 ALTER SEQUENCE forum_topics_id_seq OWNED BY forum_topics.id;
 
 
+--
+-- Name: jobs; Type: TABLE; Schema: public; Owner: -; Tablespace: 
+--
+
+CREATE TABLE jobs (
+    id integer NOT NULL,
+    category character varying(255) NOT NULL,
+    status character varying(255) NOT NULL,
+    message text NOT NULL,
+    data_as_json text NOT NULL,
+    repeat_count integer NOT NULL,
+    created_at timestamp without time zone,
+    updated_at timestamp without time zone
+);
+
+
+--
+-- Name: jobs_id_seq; Type: SEQUENCE; Schema: public; Owner: -
+--
+
+CREATE SEQUENCE jobs_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MAXVALUE
+    NO MINVALUE
+    CACHE 1;
+
+
+--
+-- Name: jobs_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: -
+--
+
+ALTER SEQUENCE jobs_id_seq OWNED BY jobs.id;
+
+
 --
 -- Name: pool_versions; Type: TABLE; Schema: public; Owner: -; Tablespace: 
 --
@@ -832,6 +867,38 @@ CREATE SEQUENCE pools_id_seq
 ALTER SEQUENCE pools_id_seq OWNED BY pools.id;
 
 
+--
+-- Name: post_moderation_details; Type: TABLE; Schema: public; Owner: -; Tablespace: 
+--
+
+CREATE TABLE post_moderation_details (
+    id integer NOT NULL,
+    user_id integer NOT NULL,
+    post_id integer NOT NULL,
+    created_at timestamp without time zone,
+    updated_at timestamp without time zone
+);
+
+
+--
+-- Name: post_moderation_details_id_seq; Type: SEQUENCE; Schema: public; Owner: -
+--
+
+CREATE SEQUENCE post_moderation_details_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MAXVALUE
+    NO MINVALUE
+    CACHE 1;
+
+
+--
+-- Name: post_moderation_details_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: -
+--
+
+ALTER SEQUENCE post_moderation_details_id_seq OWNED BY post_moderation_details.id;
+
+
 --
 -- Name: post_versions; Type: TABLE; Schema: public; Owner: -; Tablespace: 
 --
@@ -1047,6 +1114,7 @@ CREATE TABLE tags (
     view_count integer DEFAULT 0 NOT NULL,
     category integer DEFAULT 0 NOT NULL,
     related_tags text,
+    related_tags_updated_at timestamp without time zone,
     created_at timestamp without time zone,
     updated_at timestamp without time zone
 );
@@ -1445,6 +1513,13 @@ ALTER TABLE forum_posts ALTER COLUMN id SET DEFAULT nextval('forum_posts_id_seq'
 ALTER TABLE forum_topics ALTER COLUMN id SET DEFAULT nextval('forum_topics_id_seq'::regclass);
 
 
+--
+-- Name: id; Type: DEFAULT; Schema: public; Owner: -
+--
+
+ALTER TABLE jobs ALTER COLUMN id SET DEFAULT nextval('jobs_id_seq'::regclass);
+
+
 --
 -- Name: id; Type: DEFAULT; Schema: public; Owner: -
 --
@@ -1459,6 +1534,13 @@ ALTER TABLE pool_versions ALTER COLUMN id SET DEFAULT nextval('pool_versions_id_
 ALTER TABLE pools ALTER COLUMN id SET DEFAULT nextval('pools_id_seq'::regclass);
 
 
+--
+-- Name: id; Type: DEFAULT; Schema: public; Owner: -
+--
+
+ALTER TABLE post_moderation_details ALTER COLUMN id SET DEFAULT nextval('post_moderation_details_id_seq'::regclass);
+
+
 --
 -- Name: id; Type: DEFAULT; Schema: public; Owner: -
 --
@@ -1711,6 +1793,14 @@ ALTER TABLE ONLY forum_topics
     ADD CONSTRAINT forum_topics_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: jobs_pkey; Type: CONSTRAINT; Schema: public; Owner: -; Tablespace: 
+--
+
+ALTER TABLE ONLY jobs
+    ADD CONSTRAINT jobs_pkey PRIMARY KEY (id);
+
+
 --
 -- Name: pool_versions_pkey; Type: CONSTRAINT; Schema: public; Owner: -; Tablespace: 
 --
@@ -1727,6 +1817,14 @@ ALTER TABLE ONLY pools
     ADD CONSTRAINT pools_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: post_moderation_details_pkey; Type: CONSTRAINT; Schema: public; Owner: -; Tablespace: 
+--
+
+ALTER TABLE ONLY post_moderation_details
+    ADD CONSTRAINT post_moderation_details_pkey PRIMARY KEY (id);
+
+
 --
 -- Name: post_versions_pkey; Type: CONSTRAINT; Schema: public; Owner: -; Tablespace: 
 --
@@ -2159,6 +2257,20 @@ CREATE INDEX index_pools_on_creator_id ON pools USING btree (creator_id);
 CREATE INDEX index_pools_on_name ON pools USING btree (name);
 
 
+--
+-- Name: index_post_moderation_details_on_post_id; Type: INDEX; Schema: public; Owner: -; Tablespace: 
+--
+
+CREATE INDEX index_post_moderation_details_on_post_id ON post_moderation_details USING btree (post_id);
+
+
+--
+-- Name: index_post_moderation_details_on_user_id; Type: INDEX; Schema: public; Owner: -; Tablespace: 
+--
+
+CREATE INDEX index_post_moderation_details_on_user_id ON post_moderation_details USING btree (user_id);
+
+
 --
 -- Name: index_post_versions_on_post_id; Type: INDEX; Schema: public; Owner: -; Tablespace: 
 --
@@ -2463,4 +2575,8 @@ INSERT INTO schema_migrations (version) VALUES ('20100219230537');
 
 INSERT INTO schema_migrations (version) VALUES ('20100221003655');
 
-INSERT INTO schema_migrations (version) VALUES ('20100221005812');
\ No newline at end of file
+INSERT INTO schema_migrations (version) VALUES ('20100221005812');
+
+INSERT INTO schema_migrations (version) VALUES ('20100221012656');
+
+INSERT INTO schema_migrations (version) VALUES ('20100223001012');
\ No newline at end of file
diff --git a/db/migrate/20100205162521_create_tags.rb b/db/migrate/20100205162521_create_tags.rb
index 5b2f93ded..a82e82f43 100644
--- a/db/migrate/20100205162521_create_tags.rb
+++ b/db/migrate/20100205162521_create_tags.rb
@@ -6,6 +6,7 @@ class CreateTags < ActiveRecord::Migration
       t.column :view_count, :integer, :null => false, :default => 0
       t.column :category, :integer, :null => false, :default => 0
       t.column :related_tags, :text
+      t.column :related_tags_updated_at, :datetime
       t.timestamps
     end
     
diff --git a/db/migrate/20100221012656_create_jobs.rb b/db/migrate/20100221012656_create_jobs.rb
new file mode 100644
index 000000000..0edc8fe55
--- /dev/null
+++ b/db/migrate/20100221012656_create_jobs.rb
@@ -0,0 +1,16 @@
+class CreateJobs < ActiveRecord::Migration
+  def self.up
+    create_table :jobs do |t|
+      t.column :category, :string, :null => false
+      t.column :status, :string, :null => false
+      t.column :message, :text, :null => false
+      t.column :data_as_json, :text, :null => false
+      t.column :repeat_count, :integer, :null => false
+      t.timestamps
+    end
+  end
+
+  def self.down
+    drop_table :jobs
+  end
+end
diff --git a/db/migrate/20100223001012_create_post_moderation_details.rb b/db/migrate/20100223001012_create_post_moderation_details.rb
new file mode 100644
index 000000000..f6a33f96b
--- /dev/null
+++ b/db/migrate/20100223001012_create_post_moderation_details.rb
@@ -0,0 +1,16 @@
+class CreatePostModerationDetails < ActiveRecord::Migration
+  def self.up
+    create_table :post_moderation_details do |t|
+      t.column :user_id, :integer, :null => false
+      t.column :post_id, :integer, :null => false
+      t.timestamps
+    end
+    
+    add_index :post_moderation_details, :user_id
+    add_index :post_moderation_details, :post_id
+  end
+
+  def self.down
+    drop_table :post_moderation_details
+  end
+end
diff --git a/test/fixtures/hidden_posts.yml b/test/fixtures/hidden_posts.yml
new file mode 100644
index 000000000..289334110
--- /dev/null
+++ b/test/fixtures/hidden_posts.yml
@@ -0,0 +1,11 @@
+# Read about fixtures at http://ar.rubyonrails.org/classes/Fixtures.html
+
+# This model initially had no columns defined.  If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+#  column: value
diff --git a/test/fixtures/jobs.yml b/test/fixtures/jobs.yml
new file mode 100644
index 000000000..289334110
--- /dev/null
+++ b/test/fixtures/jobs.yml
@@ -0,0 +1,11 @@
+# Read about fixtures at http://ar.rubyonrails.org/classes/Fixtures.html
+
+# This model initially had no columns defined.  If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+#  column: value
diff --git a/test/unit/job_test.rb b/test/unit/job_test.rb
new file mode 100644
index 000000000..24442ff1f
--- /dev/null
+++ b/test/unit/job_test.rb
@@ -0,0 +1,8 @@
+require 'test_helper'
+
+class JobTest < ActiveSupport::TestCase
+  # Replace this with your real tests.
+  test "the truth" do
+    assert true
+  end
+end
diff --git a/test/unit/post_moderation_detail_test.rb b/test/unit/post_moderation_detail_test.rb
new file mode 100644
index 000000000..eaf09e721
--- /dev/null
+++ b/test/unit/post_moderation_detail_test.rb
@@ -0,0 +1,42 @@
+require File.dirname(__FILE__) + '/../test_helper'
+
+class PostModerationDetailTest < ActiveSupport::TestCase
+  context "A post moderation detail" do
+    should "hide posts" do
+      posts = []
+      posts << Factory.create(:post)
+      posts << Factory.create(:post)
+      posts << Factory.create(:post)
+      user = Factory.create(:user)
+      detail = PostModerationDetail.create(:user => user, :post => posts[0])
+      results = PostModerationDetail.filter(posts, user)
+      assert_equal(2, results.size)
+      assert(results.all? {|x| x.id != posts[0].id})
+      results = PostModerationDetail.filter(posts, user, true)
+      assert_equal(1, results.size)
+      assert_equal(posts[0].id, results[0].id)
+      user = Factory.create(:user)
+      results = PostModerationDetail.filter(posts, user)
+      assert_equal(3, results.size)
+      results = PostModerationDetail.filter(posts, user, true)
+      assert_equal(0, results.size)
+    end
+    
+    should "prune itself" do
+      post = Factory.create(:post, :is_flagged => true)
+      user = Factory.create(:user)
+      detail = PostModerationDetail.create(:user => user, :post => post)
+      assert_difference("PostModerationDetail.count", 0) do
+        PostModerationDetail.prune!
+      end
+      post.is_flagged = false
+      post.updater_id = user.id
+      post.updater_ip_addr = "127.0.0.1"
+      post.save
+      assert(post.errors.empty?)
+      assert_difference("PostModerationDetail.count", -1) do
+        PostModerationDetail.prune!
+      end      
+    end
+  end
+end
diff --git a/test/unit/related_tag_calculator_test.rb b/test/unit/related_tag_calculator_test.rb
new file mode 100644
index 000000000..a9bdfe60c
--- /dev/null
+++ b/test/unit/related_tag_calculator_test.rb
@@ -0,0 +1,41 @@
+require File.dirname(__FILE__) + '/../test_helper'
+
+class RelatedTagCalculatorTest < ActiveSupport::TestCase
+  context "A related tag calculator" do
+    should "calculate related tags for a tag" do
+      posts = []
+      posts << Factory.create(:post, :tag_string => "aaa bbb ccc ddd")
+      posts << Factory.create(:post, :tag_string => "aaa bbb ccc")
+      posts << Factory.create(:post, :tag_string => "aaa bbb")
+      
+      tag = Tag.find_by_name("aaa")
+      calculator = RelatedTagCalculator.new
+      assert_equal({"bbb" => 3, "ccc" => 2, "ddd" => 1}, calculator.calculate_from_sample("aaa"))
+    end
+
+    should "calculate related tags for a tag" do
+      posts = []
+      posts << Factory.create(:post, :tag_string => "aaa bbb art:ccc copy:ddd")
+      posts << Factory.create(:post, :tag_string => "aaa bbb art:ccc")
+      posts << Factory.create(:post, :tag_string => "aaa bbb")
+      
+      tag = Tag.find_by_name("aaa")
+      calculator = RelatedTagCalculator.new
+      assert_equal({"ccc" => 2}, calculator.calculate_from_sample("aaa", Tag.categories.artist))
+      calculator = RelatedTagCalculator.new
+      assert_equal({"ddd" => 1}, calculator.calculate_from_sample("aaa", Tag.categories.copyright))
+    end
+    
+    should "convert a hash into string format" do
+      posts = []
+      posts << Factory.create(:post, :tag_string => "aaa bbb ccc ddd")
+      posts << Factory.create(:post, :tag_string => "aaa bbb ccc")
+      posts << Factory.create(:post, :tag_string => "aaa bbb")
+      
+      tag = Tag.find_by_name("aaa")
+      calculator = RelatedTagCalculator.new
+      counts = calculator.calculate_from_sample("aaa")
+      assert_equal("bbb 3 ccc 2 ddd 1", calculator.convert_hash_to_string(counts))
+    end
+  end
+end