<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def enable_unique_tokens(self):
 """ Enable the use of unique access tokens on all grant types that support this option. """

        for grant_type in self.grant_types:
            if hasattr(grant_type, "unique_token"):
                grant_type.unique_token = True