Lesson — Data

KHAALI KA
MATLAB.

None matlab value hi nahi hai — missing key, empty result, no return. Isko pehchanna debugging ki superpower hai.

WHY: khaali ka matlab

Phone book me number nahi mila, API ne field nahi bheja, function ne kuch return nahi kiya — Python in sab ko None kehta hai. Matlab: value hi nahi hai. Isko pehchanna debugging ki superpower hai.

user = {"name": "Aman"}
phone = user.get("phone")
print(phone)  # None (key hai hi nahi)
print(phone is None)  # True

HOW: None se dosti

Function bina return ke None deta hai — isliye print() ka result variable me rakhna bekaar hai. Condition me None false jaisa behave karta hai, lekin compare is se karo.

def greet(name):
    print("Namaste", name)

result = greet("Aman")
print(result)  # None (return kuch nahi)

if result is None:
    print("Function ne kuch wapas nahi diya")

def find_user(uid):
    return None  # nahi mila

u = find_user(7)
if u is None:
    print("Naya account banao")

MNC tip: API me missing field handle karna — .get() + None check.

Common mistakes

• == None likhna — hamesha is None use karo.
• print() ka result variable me rakhna — wo None hota hai.
• None aur "None" (string) ko same samajhna — bilkul alag hain.