Do not lose any
item whose index is in both [lower .. upper] and
[min_index .. max_index]. New positions if any are
initialized with the appropriate default value.
Gives C access into the internal storage of the ARRAY.
Result is pointing the element at index lower.
NOTE: do not free/realloc the Result. Any operation that changes
lower or upper can make this pointer useless (because the
array has wrapped or its beginning in the storage has moved),
and operations that change capacity can make it invalid
(because new memory has been allocated and the old memory has
been freed)
The basic = is used
for comparison of items and indices are not considered (for
example this routine may yeld True with Current indexed in
range [1..2] and other indexed in range [2..3]).