Comment #14 on issue 2406 by renato.c...@gmail.com: improve Tuple
constructor
http://code.google.com/p/sympy/issues/detail?id=2406
I don't think there's any way to accomodate the signature of builtin
tuple() and the invariant imposed by `type(obj)(*obj.args) == obj` (issue
2070).
Suppose that Tuple does satisfy `type(Tuple())([1, 2, 3]) == Tuple(1, 2, 3)`
Then we would have, by the invariant, `Tuple(1, 2, 3).args == ([1, 2, 3],
)`. But actually this is not right, because it shouldn't have a list
inside, but a Tuple, so `Tuple(1, 2, 3).args == (Tuple(1, 2, 3), )`.
Now there's a funny thing: if one tries to reach the elements (1, 2 and 3)
only through `.args`, it's impossible, because `Tuple(1, 2, 3).args[0]` is
again `Tuple(1, 2, 3)`!
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