# File lib/rr/double_definitions/double_definition_create.rb, line 73
        def add_strategy(subject, method_name, definition_eval_block)
          if method_name && definition_eval_block
            raise ArgumentError, "Cannot pass in a method name and a block"
          end
          @subject = subject
          yield
          # TODO: Allow hash argument to simulate a Struct.
          if no_subject?
            self
          elsif method_name
            # TODO: Pass in arguments.
            call(method_name)
          else
            DoubleDefinitionCreateBlankSlate.new(self, &definition_eval_block)
          end
        end