def clear(self, target=None):
        """
        Clear the history
        :param target: history to clear or None for current
        :type history: str or None
        """
        if target is None:
            target = self._current
        if target in self._histories:
            del self._histories[target]

        Clear the history
        :param target: history to clear or None for current
        :type history: str or None
        
system/shhistory.py