Recursively removes empty elements (list, dicts, strings)

compress.py

import numbers

def remove_empty_nodes(struct):
    """
    In:  [1, 2, [], 0, {'a': 'b', 'c': '', 'd': {'1': []}}, [1, [2, [[], []]]]]
    Out: [1, 2, 0, {'a': 'b'}, [1, [2]]]
    """
    def keep(v):
        return isinstance(v, numbers.Number) or v

    if type(struct) == list:
        struct = [remove_empty_nodes(s) for s in struct]
        struct = filter(keep, struct)
    if type(struct) == dict:
        for k, v in struct.iteritems():
            struct[k] = remove_empty_nodes(v)
        struct = dict(
            (
                (k, v) for k, v in struct.iteritems()
                if keep(v)
            )
        )

    return struct