Викентий

let requestCounter = 0
let jsonRpcPromises = {}
function jsonrpc (method, params) {
  const dataToSend = { jsonrpc: '2.0', method, params, id: ++requestCounter }
  socket.send(JSON.stringify(dataToSend))
  return new Promise((resolve, reject) => {
    jsonRpcPromises[requestCounter] = { resolve, reject }
  })
}

function completeJsonrpc (message) {
  const { id, error, result } = message
  if (error !== undefined) {
    jsonRpcPromises[id]?.reject(error)
  } else {
    jsonRpcPromises[id]?.resolve(result)
  }
  delete (jsonRpcPromises[id])
}

//
    socket.onmessage = function (event) {
      const message = JSON.parse(event.data)
///
      if (message.jsonrpc) {
        completeJsonrpc(message)
      } else if (...) {
/// 
    }

class TestClass:
    def __init__(self, number: (int, str)):
        self._number = number

    @property
    def number(self):
        if isinstance(self._number, int):
            return self.__int_number()
        elif isinstance(self._number, str):
            return self.__str_number()
        else:
            return self._number

    @number.setter
    def number(self, value):
        self._number = value

    def __int_number(self):
        return self._number * 100

    def __str_number(self):
        return f'Hello world - {self._number}'


value_int = 150
testInstance = TestClass(value_int)
print(testInstance.number)

value_str = '0MG'
testInstance.number = value_str
print(testInstance.number)

value_another_type = ['one', 'two']
testInstance.number = value_another_type
print(testInstance.number)