Why does (1 in [1,0] == True) evaluate to False?

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Python actually applies comparison operator chaining here. The expression is translated to

(1 in [1, 0]) and ([1, 0] == True)

which is obviously False.

This also happens for expressions like

a < b < c

which translate to

(a < b) and (b < c)

(without evaluating b twice).

See the Python language documentation for further details.

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