invalid-sequence-index / E1126

Message emitted:

Sequence index is not an int, slice, or instance with __index__

Description:

Used when a sequence type is indexed with an invalid type. Valid types are ints, slices, and objects with an __index__ method.

Problematic code:

fruits = ["apple", "banana", "orange"]
print(fruits["apple"])  # [invalid-sequence-index]

Correct code:

fruits = ["apple", "banana", "orange"]
print(fruits[0])

Additional details:

Be careful with [True] or [False] as sequence index, since True and False will respectively be evaluated as 1 and 0 and will bring the second element of the list and the first without erroring.

Created by the typecheck checker.