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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def validate(self, metadata, path, value):
 """ Validate this requirement. """

        if isinstance(value, Requirement):
            # if the RHS is still a Requirement object, it was not set
            if metadata.testing and self.mock_value is not None:
                value = self.mock_value
            elif self.default_value is not None:
                value = self.default_value
            elif not value.required:
                return None
            else:
                raise ValidationError(f"Missing required configuration for: {'.'.join(path)}")

        try:
            return self.type(value)
        except ValueError:
            raise ValidationError(f"Missing required configuration for: {'.'.join(path)}: {value}")