# File lib/rspec/expectations/syntax.rb, line 75
      def enable_expect(syntax_host = ::RSpec::Matchers)
        return if expect_enabled?(syntax_host)

        syntax_host.module_eval do
          def expect(*target, &target_block)
            target << target_block if block_given?
            raise ArgumentError.new("You must pass an argument or a block to #expect but not both.") unless target.size == 1
            ::RSpec::Expectations::ExpectationTarget.new(target.first)
          end
        end
      end