def flatten(list):
    """Flatten a list of elements into a unique list
    Author: Christophe Simonis
    
    Examples:
    >>> flatten(['a'])
    ['a']
    >>> flatten('b')
    ['b']
    >>> flatten( [] )
    []
    >>> flatten( [[], [[]]] )
    []
    >>> flatten( [[['a','b'], 'c'], 'd', ['e', [], 'f']] )
    ['a', 'b', 'c', 'd', 'e', 'f']
    >>> t = (1,2,(3,), [4, 5, [6, [7], (8, 9), ([10, 11, (12, 13)]), [14, [], (15,)], []]])
    >>> flatten(t)
    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
    """
    
    def isiterable(x):
        return hasattr(x, "__iter__")

    r = []
    for e in list:
        if isiterable(e):
            map(r.append, flatten(e))
        else:
            r.append(e)
    return r

if __name__ == '__main__':
    import doctest
    doctest.testmod()