docs: def commit(self):
          '''
          :param tag:
              Checks out specified commit.
              If set to ``None`` the latest commit will be checked out
          :returns:
              A list of all commits, descending
          '''
  
          commit = self._log(num=-1, format='%H')
          if commit.get('returncode') == 0:
              return commit.get('stdout')