Varnand/Python Implementation

An implementation of Varnand written in Python 3.

import sys

code="""code goes here"""

vardict=dict(zip("abcdefghijklmnopqrstuvwxyz",[0]*26))
pnt=-1

def vareval(n): #evals int, hex string digit, var
    if isinstance(n,int):
        return n
    if n in "0123456789ABCDEF":
        return int(n,16)
    if n in vardict:
        return vardict[n]

def nand(x,y): #!
    x=vareval(x)
    y=vareval(y)
    return 255-(x&y)

def redefine(strvar,newnum): #=
    assert strvar in "abcdefghijklmnopqrstuvwxyz","Attempted to redefine non-variable"
    newnum=vareval(newnum)
    vardict[strvar]=newnum
    return newnum

def rotate(num,rot): #%
    num=vareval(num)
    t=2**(8-rot%8)
    return (num%t)*int(256/t)+num//t

def oprint(num): #O
    num=vareval(num)
    print(num,end="")
    return num

def pprint(num): #P
    num=vareval(num)
    print(chr(num),end="")
    return num

def func():
    global pnt
    pnt+=1
    if code[pnt]=="!":
        return nand(func(),func())
    elif code[pnt]=="=":
        return redefine(func(),func())
    elif code[pnt]=="%":
        return rotate(func(),func())
    elif code[pnt]=="O":
        return oprint(func())
    elif code[pnt]=="P":
        return pprint(func())
    elif code[pnt]=="I":
        return ord(sys.stdin.read(1)) #I
    elif code[pnt] in "0123456789ABCDEF":
        return int(code[pnt],16)
    elif code[pnt] in "abcdefghijklmnopqrstuvwxyz":
        return code[pnt]
    else:
        if pnt<len(code)-1:
            return func() #comments

while pnt<len(code)-1:
  func()