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: formatter.rb
    path of file: ./repos/grape/lib/grape
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Grape
  module Formatter
    extend Util::Registrable

   
    
      def formatter_for(api_format, **options)
        spec = formatters(**options)[api_format]
        case spec
        when nil
          ->(obj, _env) { obj }
        when Symbol
          method(spec)
        else
          spec
        end