return — Expert Examples

Exits a function and optionally sends a value back to the caller

EasyIntermediateAdvancedExpert

Return bytecode and optimization

How return compiles and interacts with the frame.

python
import dis

def simple():
    return 42

def implicit():
    x = 42

print("Explicit return:")
dis.dis(simple)
print("\nImplicit return (None):")
dis.dis(implicit)

# Return pushes value onto stack then RETURN_VALUE pops it
# Implicit return adds LOAD_CONST None + RETURN_VALUE

# Inspect return value behavior
print(f"\nsimple() returns: {simple()}")
print(f"implicit() returns: {implicit()}")
print(f"implicit() is None: {implicit() is None}")

Every function ends with RETURN_VALUE bytecode. Functions without explicit return get an implicit 'return None' — the compiler adds LOAD_CONST None before RETURN_VALUE.

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