[Tutor] check for nested sequences & flatten

[kevin parks]

I am trying to test for nested lists and then flatten them if need be. flatten(seq) works fine (though I wonder if this is the most efficient way to go about it --I always wondered why flatten wasn't a sequence built-in method). But here my isNested func seems broken. 

>>> isNested([1, [2], [3, [4]]])
0

# 0 is clearly wrong.

# kosher

def flatten(seq):
	"""flatten: completely eliminate nesting of any sequence type"""
	res = []
	for item in seq:
		if type(item) in (TupleType, ListType):
			res.extend(flatten(item))
		else:
			res.append(item)
	return res

# what's up with this ?
#
def isNested(seq):
	"""isNested: checks a list for nesting and if nested, exactly how deeply

	>>> isNested([1,2,3])	         yeilds: 1
	>>> isNested([1, [2], [3, [4]]])  yeilds: 3"""
	
	seq[:]
	depths = [0]
	for obj in seq:
		try:
			depths.append(isNested(obj))
		except:
			pass
	return max(tuple(depths))


# as i sure to be over my quota of questions for the day, i'll go away now.




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