# File lib/matchy/built_in/truth_expectations.rb, line 28
      def be_close(obj, delta = 0.3)
        build_matcher(:be_close, [obj, delta]) do |receiver, matcher, args|
          @receiver, expected, delta = receiver, args[0], args[1]
          matcher.positive_failure_message = "Expected #{@receiver.inspect} to be close to #{expected.inspect} (delta: #{delta})."
          matcher.negative_failure_message = "Expected #{@receiver.inspect} to not be close to #{expected.inspect} (delta: #{delta})."
          (@receiver - expected).abs < delta
        end
      end