gistfile1.py

class FooError(Exception): pass

def public_api1(x):
    """
    Return given value, after making sure it is not 1.
    
    :param x: value:
    :type x: int
    
    :raises: ForError if x == 1
    
    :return: x if not equal to 1
    :rtype: int
    """

    if x == 1:
        raise FooError('x is 1')

    return x

def public_api2(x):
    """
    Return given value after adding 5 to it, unless x == 1.
    
    :param x: value:
    :type x: int
    
    :raises: ForError if x == 1
    
    :return: x if not equal to 1
    :rtype: int
    """

    # this may raise FooError
    public_api1(x)
    x = x + 5
    return x