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: contribution_reports_for_project_owner.rb
    path of file: ./repos/catarse/app/models
    
    the code of the file until where you have to start completion: class ContributionReportsForProjectOwner < ActiveRecord::Base
  acts_as_copy_target

  belongs_to :payment

  scope :project_id, ->(project_id) { where(project_id: project_id) }
  scope :reward_id, ->(reward_id) { where(reward_id: reward_id) }
  scope :state, ->(state) { where('state in (?)', state.split(',')) }
  scope :waiting_payment, -> { where(waiting_payment: true) }
  scope :project_owner_id, ->(project_owner_id) { where(project_owner_id: proje
    
  def self.report(remove_keys=true)
    report_sql = "".dup
    keys = I18n.t('contribution_report_to_project_owner').keys
    keys.delete :open_questions if remove_keys
    keys.delete :multiple_choice_questions if remove_keys
    keys.each do |column|
      report_sql << "#{column} AS \"#{I18n.t("contribution_report_to_project_owner.#{column}")}\","
    end

    select(%(
        #{report_sql}
        CASE WHEN anonymous='t' THEN '#{I18n.t('yes')}'
            WHEN anonymous='f' THEN '#{I18n.t('no')}'
        END as "#{I18n.t('contribution_report_to_project_owner.anonymous')}"
      ))
  end