Python: Executable statements in module

A module can contain executable statements. These statements are executed; only the first time the module name is encountered in an import statement.

arithmetic.py

print("Simple api to perform arithmetic operations")
def sum(a, b):
  return a+b

def subtract(a, b):
  return a-b
  
def mul(a,b):
  return a*b
  
def div(a, b):
  return a/b

>>> import arithmetic
Simple api to perform arithmetic operations
>>> 
>>> arithmetic.sum(10, 20)
30
>>> import arithmetic
>>> 
>>> arithmetic.div(10, 20)
0.5

Observe above snippet, print statement executed only for first import of the module, not for the second import.

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