Python Coding Challenge - Question with Answer (ID -230126)

 

Explanation:

Line 1: Global Variable Initialization

x = 1

A global variable x is created.

Current value of x → 1

Line 2–5: Function Definition

def f():

    global x

    x += 2

def f():

Defines a function named f.

global x

Tells Python that x inside this function refers to the global variable, not a local one.

x += 2

Updates the global x.

When f() runs:

x becomes 1 + 2 = 3

Important:

The function does NOT return anything, so by default it returns:

None

Line 6: Function Call Inside Expression (TRICKY)

x = x + f()

Step-by-step execution order:

f() is called first

Inside f():

x becomes 3

returns None

Expression becomes:

x = 1 + None

Line 6 Result: ERROR

TypeError: unsupported operand type(s) for +: 'int' and 'NoneType'

Why?

You cannot add:

an int (1)

with None

f() returned None, not a number

Line 7: Print Statement

print(x)

This line never runs, because the program crashes on the previous line.

Final Outcome

Output:

TypeError

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