12.2.2 The stack

When an exception is raised, you see the call stack. The call stack contains the trace of all the functions that called the code where the exception was raised.

A simple stack example is:

def f():
   g()
def g():
   h()
def h():
   1//0

f()

The stack, in this case, is f, g, and h. The output generated by running this piece of code looks like this:

Traceback (most recent call last):
  File "stack_example.py", line 11, in <module>
    f() 
  File "stack_example.py", line 3, in f
    g() 
  File "stack_example.py", line 6, in g
    h() File "stack_example.py", line 9, in h
    1//0 
ZeroDivisionError: integer division or modulo by zero

The error is printed. The sequence of functions leading up to the error is shown. The function f on line 11 was called, which in turn called g and then h. This caused ZeroDivisionError.

A stack trace reports on the active stack at a certain...