New feature in #Tcl9 – part 32:

lsearch ... -stride ... — Search a list by groups of items

[lsearch ...] is powerful. For flat lists, the -stride option in Tcl 9 can kind of pretend that your list is "nested". In fact, it groups a number of items and treat them as a unit:

lsearch -stride 3 {a A amen b B bank c C citron} c
6

Here, each three elements "a a amen", "b B bank" and so on are regarded as one group. Together with the `-index` option, you can search in any group element!