(49G/50g) Shortest code to increment a variable?

[Gil]

Note also that STO+
can be used with a variable that contains a list.

Suppose you have done {1 2 3} 'A' STO.
Then try 20 'A' STO+
and press A
to see the new list A {20 1 2 3},
with the number added as the first element of the list A.

Try now with "test" 'A' STO+
and press A
to see the new list A {"test" 20 1 2 3}.

Instead of a string,
you could have a variable name such as 'B':
Try 'B' 'A' STO+
and press A
to see the new list A {B "test" 20 1 2 3}.