<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_counters(self, *sequences):
 """Prepare sequences and convert it to Counters. """

        # already Counters
        if all(isinstance(s, Counter) for s in sequences):
            return sequences
        return [Counter(s) for s in self._get_sequences(*sequences)]