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"""
Providing iterator functions that are not in all version of Python we support.
Where possible, we try to use the system-native version and only fall back to
these implementations if necessary.
"""
import itertools
def compat_tee(iterable):
"""Return two independent iterators from a single iterable.
Based on http://www.python.org/doc/2.3.5/lib/itertools-example.html
"""
# Note: Using a dictionary and a list as the default arguments here is
# deliberate and safe in this instance.
def gen(next, data={}, cnt=[0]):
dpop = data.pop
for i in itertools.count():
if i == cnt[0]:
item = data[i] = next()
cnt[0] += 1
else:
item = dpop(i)
yield item
next = iter(iterable).next
return gen(next), gen(next)
if hasattr(itertools, 'tee'):
tee = itertools.tee
else:
tee = compat_tee
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