polymorphism means one function with multiple forms. one function can act like multiple functions.
Example:
#polymorphism
print(len("hello"))
print(len([10,20,30]))
output:
5
3
#your defined polymorphism
def poly_test(a,b,c=0):
print(a+b+c)
poly_test(10,20)
poly_test(10,20, c=30)
output :
30
60