Sequence_generic needs to guard __iadd__, __imul__, __delitem__ if "immutable". #19813
Description
I don't even:
sage: b = VectorSpace(QQ,3).basis()
sage: b += ["Hello, world!"]
sage: VectorSpace(QQ,3).basis()
[
(1, 0, 0),
(0, 1, 0),
(0, 0, 1),
'Hello, world!'
]
See also #19251.
CC: @mjungmath @tscrim
Component: linear algebra
Author: Matthias Koeppe, ...
Branch/Commit: u/mkoeppe/sequence_generic_needs_to_guard_iadd__imul__delitem__delslice_if__immutable__ @ 18bb870
Issue created by migration from https://trac.sagemath.org/ticket/19813