<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _call_lset(self, command, index, value, *args, **kwargs):
 """ Before setting the new value, get the previous one to deindex it. Then call the command and index the new value, if exists """

        if self.indexable:
            old_value = self.lindex(index)
            self.deindex([old_value])
        result = self._traverse_command(command, index, value, *args, **kwargs)
        if self.indexable:
            self.index([value])
        return result