**NOTE**: When called on an empty corpus (no documents), will return False.
try:
if hasattr(obj, "next"):
return False // iterators are not allowed to be corpora (need an iterable)
doc1 = iter(obj).next() // obj supports iteration and is not empty
if len(doc1) == 0: // the first document is empty
return True
id1, val1 = iter(doc1).next() // or the first document is a 2-tuple
id1, val1 = int(id1), float(val1) // id must be an integer, weight a float
After Change
// the input is an iterator (not iterable), meaning once we call next()
// that element is gone forever. we must be careful to put whatever we
// retrieve back again
doc1 = obj.next()obj = itertools.chain([doc1], obj)
else:
doc1 = iter(obj).next()
if not list(doc1):
return True, obj // the first document is empty, assume this is a corpus
