code: func (h *Client) SessionControl(sessionControl string) *Client {
  	h.sessionControl = sessionControl
  	h.sessionControlSet = true
  	return h
  }
docs: // Used to control the session duration. A value of 'start'
  // forces a new session to start with this hit and 'end' forces
  // the current session to end with this hit. All other values
  // are ignored.