Message Decode

def decode(message, shift):
    mesg,order="",0
    for m in message:

#-ive sign will automatically shift decoding in desired directions
        order=ord(m)-shift

#normal ASCII range 65-90 OR 97-122
        if 65<=ord(m)<=90 and 65<=order<=90: mesg=mesg+chr(order)
        elif 97<=ord(m)<=122 and 97<=order<=122: mesg=mesg+chr(order)

#for positive shift
        elif 65<=ord(m)<=90 and 91<=order<106: mesg=mesg+chr(order-26)
        elif 97<=ord(m)<=122 and 123<=order<148: mesg=mesg+chr(order-26)

#for negative shift
        elif 65<=ord(m)<=90 and 40<=order<65: mesg=mesg+chr(order+26)
        elif 97<=ord(m)<=122 and 72<=order<97: mesg=mesg+chr(order+26)

#add whitespaces, special characters as it is
        else: mesg=mesg+m
    message=mesg
    return message