docs: def pre_start_check(self):
          """
          Check if process accepts connections.
  
          .. note::
  
              Process will be considered started, when it'll be able to accept
              TCP connections as defined in initializer.
          """
          try:
              sock = socket.socket()
              sock.connect((self.host, self.port))
              return True
          except (socket.error, socket.timeout):
              return False
          finally:
              # close socket manually for sake of PyPy
              sock.close()