python monkey patch a library code example

Example: monkey patching in python

In Python, the term monkey patch refers to dynamic (or run-time) modifications of a class or module. In Python, we can actually change the behavior of code at run-time.
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# monk.py 
class A: 
     def func(self): 
          print ("func() is being called") 

We use above module (monk) in below code and change behavior of func() at run-time by assigning different value.
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import monk 
def monkey_f(self): 
     print ("monkey_f() is being called") 
# replacing address of "func" with "monkey_f" 
monk.A.func = monkey_f 
obj = monk.A() 
# calling function "func" whose address got replaced 
# with function "monkey_f()" 
obj.func()