Convert strings to numbers

def convert_string_to_number(value):
    """
    Convert strings to numbers
    """
    if value is None:
        return 1
    if isinstance(value, int):
        return value
    if value.isdigit():
        return int(value)
    num_list = map(lambda s: NUMBERS[s], re.findall(numbers + '+', value.lower()))
    return sum(num_list)