def read_numeric_forcefully(line, default=None):
    if default != '':
        line = line + ' (default is ' + str(default) + ', to accept just hit return)'
    value = input(line + ': ').strip()
    if value == '':
        if default is None:
            print('- This information is really necessary, please enter a number!')
            return read_numeric_forcefully(line)
        else:
            print('- Using the default value, ' + str(default))
            return int(default)
    else:
        return int(value)