Code to Implement

remove_first

fun remove_first(xs : a list, target : a) : a list =
    raise NotYetImplemented

Remove the first item which matches target if it exists. For example, remove_first([1,2,3,4,5], 3) should return the list [1,2,4,5].

If the target does not exist, return the complete list. For example, remove_first([1,2,3,4,5], 6) should return the list [1,2,3,4,5].

file:	unit_test_warmup_remove_first.sml
source folder:	src/test/sml/remove_first