From Tcl 8.5, list non-inclusion expr operator. E.g.
if {$el ni $list} ...Opposite of in. - rs 2007-04-26
set el Mon
set list [list Mon Tue Wed Thu Fri Sat Sun]
if {$el ni $list} {
puts "Invalid day abbreviation"
} else {
puts "Valid day abbreviation"
}
Category Command a subcommand of expr