An INDEXABLE[E_] is a finite readable sequence of objects of type E_.
A good performance should always be obtained by sequentially accessing an INDEXABLE with increasing
indexes (from lower to upper), as demonstrated in the following code snippet :
from
i := a_indexable.lower
until
i > a_indexable.upper
loop
do_something_with(a_indexable.item(i))
i := i + 1
end
Other accessing methods (including random access and sequential access from upper to lower) may or
may not lead to acceptable performance, depending on the particular implementation of INDEXABLE.