Generic flatten function for Python

flatten.py

def flatten(obj, *args, depth=1):
    """Generic function for flattening nested sequences.
    
    Parameters
    ----------
    obj : iterable
        iterable sequence
    args : list of type
        one or more iterable types to flatten
    depth : int
        limit for recursion depth, use -1 for no limit
        
    Returns
    -------
    generator
        flattened sequence of values
        
    Notes
    -----
    Specifying depth -1 when flattening strings will
    result in a RecursionError.
    
    Examples
    --------
    >>> seq = (1, 2, 3, [4, 5, (6,)], 7, [8, 9])
    >>> tuple(flatten(seq, tuple, list, depth=-1))
    (1, 2, 3, 4, 5, 6, 7, 8, 9)
    
    """
    if depth == 0:
        yield obj
    elif any(isinstance(obj, t) for t in args):
        for i in obj:
            yield from flatten(i, *args, depth=depth-1)
    else:
        yield obj