import numpy as np
def IterFlatten(iterable):
    u"""итератор по вложенным перечисляемым объектам
>>> [i for i in IterFlatten([1,34.5,2,3,[[],[6,7,{'a':'b','c':'d'}]]])]
[1, 34.5, 2, 3, 6, 7, 'a', 'c']"""
    if type(iterable) is np.matrix:
        iterable=np.array(iterable)
    if hasattr(iterable,"__iter__"):
        for seq in iterable:
            for e in IterFlatten(seq):
                yield e
    else:
        yield iterable
def Flatten(iterable,level=None):
    u"""удаление внутренней структуры у списков
>>> Flatten([1,34.5,2,3,[[],[6,7,{'a':'b','c':'d'}]]])
[1, 34.5, 2, 3, 6, 7, 'a', 'c']"""
    return list(IterFlatten(iterable))

f = lambda ls: reduce(lambda res, x: res+[x] if not isinstance(x,list) else res + f(x),ls,[])

f([['define', ['if', '1', ['*', 'n', ['fac', ]]]]])
Out[3]: ['define', 'if', '1', '*', 'n', 'fac']