def and_return(response=nil, &block)
      new_response = (response.nil? ? block : response)
      responses.push(*new_response)
    end
def and_return(response=nil, &block)
      new_response = (response.nil? ? block : response)
      responses.push(*new_response)
    end
Specify what should be returned,
 when this expectation is hit.

 @example Add response.
   expectation.and_return(response)

 @return [ void ]