is vs == - Khi nào dùng cái nào?

a = [1, 2, 3]
b = [1, 2, 3]
print(a == b)  # True - Cùng giá trị

a = [1, 2, 3]
b = [1, 2, 3]
print(a is b)  # False - Khác object
 
c = a
print(a is c)  # True - Cùng object

# ✅ ĐÚNG
if value is None:
    pass
 
# ❌ SAI
if value == None:
    pass

# ✅ OK
if flag is True:
    pass
 
# ✅ Nhưng tốt hơn
if flag:
    pass

if a is b:
    print("Cùng object")

# ✅ Strings
if name == "Alice":
    pass
 
# ✅ Numbers
if count == 10:
    pass
 
# ✅ Lists/dicts
if data == expected:
    pass

# Strings
a = "hello"
b = "hello"
print(a is b)  # True (interned)
 
# Integers
x = 256
y = 256
print(x is y)  # True (cached)
 
x = 257
y = 257
print(x is y)  # False (not cached)

if value is None:  # Identity
if value == expected:  # Equality