how to set breakpoint in python pdb code example

Example 1: how to set breakpoint in python pdb

import pdb

<SOME_CODE>
pdb.set_trace()

###  OR  ###
from pdb import set_trace as bp

<SOME_CODE>
bp()

Example 2: pdb debugger

import pdb
def fact(x):
   f = 1
   for i in range(1,x+1):
      pdb.set_trace()
      print (i)
      f = f * i
   return f
if __name__=="__main__":
   print ("factorial of 3=",fact(3))