In what order does Python read the codes? (Sample Code included)

Question

I am currently learning how to code in Python and I have stumbled across this code in the book I am learning from (Learning Python the Hard Way [I don't recommend to anyone that JUST started coding btw]).

from sys import exit
def gold_room():
    print "This room is full of gold. How much do you take?"

    next = raw_input("> ")
    if "0" in next or "1" in next:
        how_much = int(next)
    else:
        dead("Man, learn to type a number.")

    if how_much < 50:
        print "Nice, you're not greedy, you win!"
        exit(0)
    else:
        dead("You greedy bastard!")

def bear_room():
    print "There is a bear here."
    print "The bear has a bunch of honey."
    print "The fat bear is in front of another door."
    print "How are you going to move the bear?"
    bear_moved = False

    while True:
        next = raw_input("> ")

        if next == "Take honey":
            dead("The bear looks at you then slaps you.")
        elif next == "taunt bear" and not bear_moved:
            print "The bear has moved from the door. You can go through it now."
            bear_moved = True
        elif next == "Taunt Bear" and bear_moved:
            dead("The bear gets pissed off and chews your legs off.")
        elif next == "open door" and bear_moved:
            gold_room()
        else:
            print "I got no idea what that means."

def cthulhu_room():
    print "Here you see the great evil Cthulhu."
    print "He, it, whatever stares at you and you go insane."
    print "Do you flee for your life or eat your head?"

    next = raw_input("> ")

    if "flee" in next:
        start()
    elif "head" in next:
        dead("Well that was tasty!")
    else:
        cthulhu_room()

def dead(why):
    print why, "Good job!"
    exit(0)

def start():
    print "You are in a dark room."
    print "There is a door to your right and left."
    print "Which one do you take?"

    next = raw_input("> ")

    if next == "left":
        bear_room()
    elif next == "right":
        cthulhu_room()
    else:
        dead("You stumble around the room until you starve.")

start()

I have always thought that Python reads codes from left to right and from up to down but in the code above, it starts running the program from def start(): print "You are in a dark room." I don't understand what is making Python do this, if anyone can clear this up for me it would be of great help. Thanks a lot in advance.

Answer 1

I have always thought that Python reads codes from left to right and from up to down

Reads, yes, top-down, left to right.

The def gold_room(): only defines function gold_room , it does not run it. Without gold_room() somewhere below, it will never be executed. Same with start() .