How are arguments passed by value or by reference in Python?

Python uses a mechanism, which is known as "Call-by-Object", sometimes also called "Call by Object Reference" or "Call by Sharing"

If you pass immutable arguments like integers, strings or tuples to a function, the passing acts like Call-by-value. It's different, if we pass mutable arguments.

All parameters (arguments) in the Python language are passed by reference. It means if you change what a parameter refers to within a function, the change also reflects back in the calling function.

Example

student={'Archana':28,'krishna':25,'Ramesh':32,'vineeth':25}
def test(student):
   new={'alok':30,'Nevadan':28}
   student.update(new)
   print("Inside the function",student)
   return
test(student)
print("outside the function:",student)

Output

Inside the function {'Archana': 28, 'krishna': 25, 'Ramesh': 32, 'vineeth': 25, 'alok': 30, 'Nevadan': 28}
outside the function: {'Archana': 28, 'krishna': 25, 'Ramesh': 32, 'vineeth': 25, 'alok': 30, 'Nevadan': 28}