String substitution for names and docstrings.

def with_args(self, **kwargs):
    """String substitution for names and docstrings."""
    validators = [
        validator.with_args(**kwargs)
        if hasattr(validator, 'with_args') else validator
        for validator in self.validators
    ]
    return mutablerecords.CopyRecord(
        self, name=util.format_string(self.name, kwargs),
        docstring=util.format_string(self.docstring, kwargs),
        validators=validators,
        _cached=None,
    )