why is none written at the end?

Question

def spam(x):
"""this is a doc string"""
if x==10:
print("x is 10")

print(spam.__doc__)
print(spam(10))

Answer 1

In the last line of the function, write
return ("x is 10")
instead of
print ("x is 10")

Answer 2

You don't returning anything from function and trying to print returned value..
Just use

spam(10)