<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def signature(self):
 """Get data signature"""

        self._data.sort()
        str_to_sign = self._delimiter.join(self._data)
        return hashlib.sha1(str_to_sign).hexdigest()