code: def _get_version_output(self):
          
          if not self.executable:
              return ''
          command = [self.executable, '--version']
          out, _, _ = self._check(self.conn, command)
          try:
              return out.decode('utf-8').split()[2]
          except IndexError:
              return ''
docs: Ignoring errors, call `ceph --version` and return only the version
          portion of the output. For example, output like::
  
              ceph version 9.0.1-1234kjd (asdflkj2k3jh234jhg)
  
          Would return::
  
              9.0.1-1234kjd