<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def build_ttfs(self, ufos, **kwargs):
 """Build OpenType binaries with TrueType outlines."""

        self.save_otfs(ufos, ttf=True, **kwargs)