code: def _call(self, cmd, get_output):
          
          server_err = self.server_logger()
  
          chan = self.get_client().get_transport().open_session()
          try:
              logger.debug("Invoking %r%s",
                           cmd, " (stdout)" if get_output else "")
              chan.exec_command('/bin/sh -c %s' % shell_escape(cmd))
              output = b''
              while True:
                  r, w, e = select.select([chan], [], [])
                  if chan not in r:
                      continue  # pragma: no cover
                  recvd = False
                  while chan.recv_stderr_ready():
                      data = chan.recv_stderr(1024)
                      server_err.append(data)
                      recvd = True
                  while chan.recv_ready():
                      data = chan.recv(1024)
                      if get_output:
                          output += data
                      recvd = True
                  if not recvd and chan.exit_status_ready():
                      break
              output = output.rstrip(b'\r\n')
              return chan.recv_exit_status(), output
          finally:
              server_err.done()
              chan.close()
docs: Calls a command through the SSH connection.
  
          Remote stderr gets printed to this program's stderr. Output is captured
          and may be returned.