Stage 5 · Bellows Bridge

Functions & return

“A spell that returns nothing builds nothing, little ember.”Bellows Sage

Scrolls on the trail

These are the 5 lore scrolls you'll find in Bellows Bridge, in the order the lesson teaches them. The comment after each print shows what it outputs.

Lore scroll · Functions & return

Naming a Spell

def double(n):
    return n * 2
print(double(4))   # 8
print(double(10))  # 20

def names a block of code. Calling double(4) runs it with n set to 4.

Lore scroll · Functions & return

Handing Back

def shout(word):
    return word.upper()
loud = shout("ash")
print(loud + "!")  # ASH!

return hands a value back to the caller, to store in a name or use at once.

Lore scroll · Functions & return

Nothing Returned

def hum():
    print("mm")  # mm
print(hum())     # None

print shows a value but hands nothing back. With no return, a call gives None.

Lore scroll · Functions & return

Default Arguments

def heat(n, by=2):
    return n + by
print(heat(5))      # 7
print(heat(5, 10))  # 15

by=2 is a default: used when the call leaves it out, replaced when it doesn't.

Lore scroll · Functions & return

Inside Stays Inside

x = 1
def bump():
    x = 9
    return x
print(bump(), x)  # 9 1

A name set inside a function is its own. The x outside is left alone.

The stage puzzle: The span bridge

In-game view of The span bridge in Bellows Bridge

The chasm is fourteen tiles wide, too far for any jump. Four call blocks marked 3, 4, 5 and 6 hang before the edge. Bumping one calls span with that number and lays a plank bridge as long as the value it returns. Too short and the planks fall into the chasm. Too long and they hit the far cliff and break.

Slate in the stage

def span(n):
    return n * 2 + 4
bridge = span(?)  # gap 14

Show the answer

span(5) returns 5 * 2 + 4 = 14, the exact width of the gap.

Practice the Bellows Sage's trial

In the game, the Bellows Sage duels you in a sealed arena. His question shows across the top of the screen, and you answer by jumping up into the lettered block, A to D, while you dodge his spells. You need 4 right answers to banish him. These are his questions, drawn from all 11 in his bank. The hints work the same as in the game: ask once for his riddle, and ask again for him to rule out a wrong answer.