# Demo, simple calculator.
grammar = compile_grammar(r"""
expr = factor ([+-] factor)*
factor = primary ([*/] primary)*
number = &("."? [0-9]) [0-9]* ("." [0-9]*)? # The first part is to make sure this doesn't match ".".
primary = "(" expr ")" / number / "-" primary
""")

def eval_expr(expr):
    r = eval_factor(expr[0])
    for f in expr[1]:
        if str(f[0]) == "+": r += eval_factor(f[1])
        else:                r -= eval_factor(f[1])
    return r

def eval_factor(factor):
    r = eval_primary(factor[0])

>>> map(hex,map(ord,"OK"))
['0x4f', '0x4b']

for user in chatroom:
    say(user, "Hi!")

say("Hi!")

Error: chatroom undefined

>┬───────────────────┐
 │ This is a comment │
 └───────────────────┴
▒┬───────────────────┐
 │ This is a comment │
 └───────────────────┴
>▒───────────────────┐
 │ This is a comment │
 └───────────────────┴
>┬▒──────────────────┐
 ▒ This is a comment │
 └───────────────────┴
>┬─▒─────────────────┐
 │ This is a comment │
 ▒───────────────────┴
16 cycles later...
>┬─────────────────▒─┐
 │ This is a comment │
 └───────────────▒───┴
>┬──────────────────▒┐
 │ This is a comment │
 └────────────────▒──┴

2016-04-29T09:29:49
-------------------
DD-M H:MI:SS
------------
29-4 9:29:49
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2949-2949
---------
2949
2949