h_drop_from_sequence(h_sequence, ...)
This combinator would drop any number of results from an h_sequence.
The variadic arguments would all be uints, and represent indices into the TT_SEQUENCE.
Written in Lua b.c it's easier:
local abcd = h.sequence(h.token "a", h.token "b", h.token "c" , h.token "d")
local ac = h.drop_from_sequence(abcd, 2, 4)
ac:parse "abcd"
-- returns {"a", "c"}