code: func (h *handler) handleCall(cp *callProc, msg *jsonrpcMessage) *jsonrpcMessage {
  	if msg.isSubscribe() {
  		return h.handleSubscribe(cp, msg)
  	}
  	var callb *callback
  	if msg.isUnsubscribe() {
  		callb = h.unsubscribeCb
  	} else {
  		callb = h.reg.callback(msg.Method)
  	}
  	if callb == nil {
  		return msg.errorResponse(&methodNotFoundError{method: msg.Method})
  	}
  	args, err := parsePositionalArguments(msg.Params, callb.argTypes)
  	if err != nil {
  		return msg.errorResponse(&invalidParamsError{err.Error()})
  	}
  
  	return h.runMethod(cp.ctx, msg, callb, args)
  }
docs: // handleCall processes method calls.