Since Postgres 9.5 it is possible to use the => operators for filling in
named parameters in a function call, like perform my_func(named_param =>
'some value'). The old form, with the := operator is still allowed for
backward reference.
But with open cursor, still only the old := operator is allowed.
Wouldn't it be more appropriate to at least allow the => operator there
as well, like open my_cursor(named_param => 'some value')?
