Declaring A Function Argument As Global?

[Skip Montanaro]

    >> def lhandler(list):
    >>     list[:] = list[1:]

    Tim> 'Works like a charm.  But why?

list[:] on the left-hand side of an assignment assigns to the entire list.
It's effectively 

    list[0:len(list)] = rhs

See

    http://www.python.org/doc/current/ref/slicings.html
    http://www.python.org/doc/current/tut/node5.html#SECTION005140000000000000000

for further discussion of list slicing.

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