The from_callback operator is a higher order function. It returns a function that returns an observable. This observable emits a single item: the result of a callback function provided as a parameter of the operator. This callback function is called when the observable is being subscribed. The marble diagram of this operator is shown in the following figure:
Figure 4.10: The from_callback operator
Its prototype is as follows:
Observable.from_callback(func, selector=None)
The return value of the from_callback operator is a function. This function returns an observable, and must be called with the parameters to pass ...
