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: descriptions.rb
    path of file: ./repos/gitlabhq/rubocop/cop/graphql
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

# This cop checks for missing GraphQL descriptions and enforces the description style guide:
# https://docs.gitlab.com/ee/development/api_graphql_styleguide.html#description-style-guide
#
# @safet
    
        def on_send(node)
          return unless graphql_describable?(node)
          return if resolver_kwarg(node) # Fields may inherit the description from their resolvers.

          description = locate_description(node)

          message = if description.nil?
                      MSG_NO_DESCRIPTION
                    elsif no_period?(description)
                      MSG_NO_PERIOD
                    elsif bad_start?(description)
                      MSG_BAD_START
                    elsif contains_demonstrative_this?(description)
                      MSG_CONTAINS_THIS
                    end