I
agree, that syntax definitely seems counter-intuitive. If it came up in
a code review, I would request a revision to "A in B and B < C".
Please recall that chained comparisons such are
>>> A < B < C
is to produce simple code when B is not an identifier, but an expression. For example
>>> low < len(x) < high
or
>>> inner ** 2 < x**2 + y**2 + z**2 < outer**2
which determines if (x, y, z) is in a spherical shell.
Even for "A < B < C" it might be better to have "A < B and B < C". Particularly if B and C are complicated expressions.
--
Jonathan