converting a number from bytes to float and back

[scidam]

You can implement a decorator to force output type, e.g.

from functools import wraps
def retain_type(f):
    @wraps(f)
    def wrapper(inp):
        res = f(inp)
        if type(res) == type(inp):
            return res
        elif isinstance(res, str):
            return res.encode('utf-8')
        elif isinstance(res, bytes):
            return res.decode('utf-8')
        else:
            raise TypeError("Output type shoud be either bytes or str.")
    return wrapper

@retain_type
def inc(num):
    if isinstance(num, bytes):
        num = num.decode('utf-8')
    return type(num)(float(num)+1)