The pid of this process.

    :raises: Will raise a ``Process.UnboundProcess`` exception if the
             process is not bound to a context.

def pid(self):
    """The pid of this process.

    :raises: Will raise a ``Process.UnboundProcess`` exception if the
             process is not bound to a context.
    """
    self._assert_bound()
    return PID(self._context.ip, self._context.port, self.name)