Python's nesting function for stepping on pits

It is important to note that Python is the language of the interpretation type. Allows function A to call function B without defining a B function before defining a function.

def func1():    print"Hello fun1"    fun2()def func2():    print"Hello func2"fun1()

It is possible to do so. But imagine if function 2 also calls function 1?

As follows:

def func1():    print"Hello fun1"    fun2()def func2():    print"Hello func2"    fun1()fun1()

This is a nested call. Will explode the stack of ...
Because it is not a compiled language, this problem is difficult to pre-parse the syntax, it is likely that python in order to pursue speed, not to analyze the error.
So when writing a program, pay special attention to not nesting calls between two or more functions ...
Of course, I didn't do it, I just tried it, so python can actually nest defined functions.

Python's nesting function for stepping on pits