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How to reproduce
----------------
Take the following two functions:
 >>> def f(l, (x, y)):
 ... sup = max(u*x + v*y for u, v in l)
 ... return ((u, v) for u, v in l if u*x + v*y == sup)
 >>> def g((x, y)):
 ... def h():
 ... return x + y
 ... return h
Inspect.getargs will throw an exception on the former and return a wrong
result on the latter::
 >>> import inspect
 >>> inspect.getargs(f.__code__)
 Traceback (most recent call last):
 ...
 IndexError: list index out of range
 >>> inspect.getargs(g.__code__)
 Arguments(args=['h'], varargs=None, keywords=None)
 # h is most definitely not an argument of g!
Analysis
--------
If you disassemble the two functions, you'll see that in both cases
the anonymous tuples are unpacked using STORE_DEREF::
 >>> import dis
 >>> dis.disassemble(f.__code__)
 1 0 LOAD_FAST 1 (.1)
 3 UNPACK_SEQUENCE 2
 6 STORE_DEREF 0 (x)
 9 STORE_DEREF 2 (y)
 <BLANKLINE>
 2 12 LOAD_GLOBAL 0 (max)
 ...
 >>> dis.disassemble(g.__code__)
 1 0 LOAD_FAST 0 (.0)
 3 UNPACK_SEQUENCE 2
 6 STORE_DEREF 0 (x)
 9 STORE_DEREF 1 (y)
 <BLANKLINE>
 2 12 LOAD_CLOSURE 1 (y)
 15 LOAD_CLOSURE 0 (x)
 18 BUILD_TUPLE 2
 21 LOAD_CONST 1 (<code object h ...>)
 24 MAKE_CLOSURE 0
 27 STORE_FAST 3 (h)
 <BLANKLINE>
 4 30 LOAD_FAST 3 (h)
 33 RETURN_VALUE \
However, the implementation of inspect.getargs only looks for
UNPACK_TUPLE, UNPACK_SEQUENCE, STORE_FAST.
Notes
-----
The version of Python used is::
 >>> import sys
 >>> sys.version_info[:3]
 (2, 7, 3)