'This is called as a callback once we have received a Connection.Start
from the server.
:param pika.frame.Method method_frame: The frame received
:raises: UnexpectedFrameError'

def _on_connection_start(self, method_frame):

    self._set_connection_state(self.CONNECTION_START)
    if self._is_protocol_header_frame(method_frame):
        raise exceptions.UnexpectedFrameError
    self._check_for_protocol_mismatch(method_frame)
    self._set_server_information(method_frame)
    self._add_connection_tune_callback()
    self._send_connection_start_ok(*self._get_credentials(method_frame))
