isinstance now accepts a tuple containing classes 
and/or types as second argument.
The patch abstract.diff implements a better error 
message:

isinstance arg 2 must be a class, type or tuple of 
classes and types

instead of

isinstance arg 2 must be a class or type

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We should update the docstring too.

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The doc-string seems ok. Here is it from 2.2.1:

isinstance(object, class-or-type-or-tuple) -> Boolean

Return whether an object is an instance of a class or of a 
subclass thereof.
With a type as second argument, return whether that is the 
object's type.
The form using a tuple, isinstance(x, (A, B, ...)), is a shortcut 
for
isinstance(x, A) or isinstance(x, B) or ... (etc.).

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Sorry about that, 2.1.x was the last version where the
docstring didn't have tuple.

Patch looks good to me.

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Isn't there a komma missing between "type" and "or"?

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Right.

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I've attached a new patch.

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Checked in as revision 2.102.