sequence function: sread-range
sread-range(start-idx, finish-idx) input-seq
the sequence read-range function
acts just like sselect[a,b] except a and b are now kets, not constants.
is also almost the same as: sread(range(start-idx, finish-idx)) input-seq
but there are some differences. eg, sread-range can handle negative indices too.
index values start at 1, not 0. So 1 is the first element, 2 is the 2nd element, and so on.
negative index values work too. eg, -1 is the last element in the sequence, -2 is the 2nd last, and so on.
if the index value is > length of input-seq, then those index values are ignored
-- standard usage:
sread-range(|2>, |5>) ssplit |abcdefgh>
|b> . |c> . |d> . |e>
-- with negative index value:
sread-range(|2>, |-3>) ssplit |abcdefgh>
|b> . |c> . |d> . |e> . |f>
sread, swrite, swrite-range, sselect