Functions, arguments & scope

1. Anatomy of a functionAsk Grok Bot

def notional(qty, px, fx=1.0):
    """Trade value in USD."""
    return qty * px * fx

notional(100, 99.5)            # positional
notional(qty=100, px=99.5, fx=1.36)  # keyword

def creates a function object and binds a name to it. return sends a value back; without it the function returns None. Defaults like fx=1.0 are evaluated once (recall the mutable-default trap from Lesson 1).