<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def new_tag(self, name: str, category: str=None) -> models.Tag: """Create a new tag."""

        new_tag = self.Tag(name=name, category=category)
        return new_tag