Inconsistency in Python programming language?

[Gribouillis]

What about ++++45 or -+54 ? Here is a corrected version

def func(s):
    t = re.sub(r'\s+', '', s)
    f = io.StringIO(t)
    for tok in generate_tokens(f.readline):
        if tok[1] in ('-', '+'):
            continue
        if tok[0] == NUMBER:
            return ast.literal_eval(t[:tok[3][1]])
        return 0
    return 0