# Count and update length of collisions for `node_at_idx`
	# Note for dynamic call-graph analysis: callers of this functions are
	# responsible of collisions.
	fun gt_collide(i: Int, k: K)
	do
		var c = _array[i]
		sys.gt_coll += 1
		while c != null do
			sys.gt_tot_coll += 1
			c = c._next_in_bucklet
		end
	end