You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20170827000729_remove_conferences.rb
    path of file: ./repos/mushroom-observer/db/migrate
    
    the code of the file until where you have to start completion: class RemoveConferences < ActiveRecord::Migration
  def up
    drop_table :conference_registrations
    drop_table :conference_events
  end

  def down
    create_table :conference_events,
                 options: "ENGINE=InnoDB DEFAULT CHARSET=utf8",
                 force: true do |t|
      t.column "name", :string, limit: 1024
      t.column "location", :string, limit: 1024
      t.column "start", :date
      t.column "end", :date
      t.column "created_at", :datetime
      t.colum
    
  def down
    create_table :conference_events,
                 options: "ENGINE=InnoDB DEFAULT CHARSET=utf8",
                 force: true do |t|
      t.column "name", :string, limit: 1024
      t.column "location", :string, limit: 1024
      t.column "start", :date
      t.column "end", :date
      t.column "created_at", :datetime
      t.column "updated_at", :datetime
      t.column "description", :text, limit: 65535
      t.column "registration_note", :text, limit: 65535
    end

    create_table :conference_registrations,
                 options: "ENGINE=InnoDB DEFAULT CHARSET=utf8",
                 force: true do |t|
      t.column "conference_event_id", :integer
      t.column "name", :string, limit: 1024
      t.column "email", :string, limit: 1024
      t.column "created_at", :datetime
      t.column "updated_at", :datetime
      t.column "how_many", :integer
      t.column "verified", :datetime
      t.column "notes", :text
    end
  end