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...