code: def _assertion(self, matcher, value):
          
          # To support the syntax `any_of(subject) | should ...` we check if the
          # value to check is an Expectation object and if it is we use the descriptor
          # protocol to bind the value's assertion logic to this expectation.
          if isinstance(value, Expectation):
              assertion = value._assertion.__get__(self, Expectation)
              assertion(matcher, value.value)
          else:
              hc.assert_that(value, matcher)
docs: Perform the actual assertion for the given matcher and value. Override
              this method to apply a special configuration when performing the assertion.
              If the assertion fails it should raise an AssertionError.