sorcery  Diff

		local leaftype = treedef and treedef.leaves or nil
		if not leaftype then return false end

		local uppermost, lowermost
		local found_leaves = false

		local treemap, treenodes = amass(pos,function(node, where)
			print(where, 'treetype',treetype,'node',node.name,node.param1,node.param2)
			if node.name == treetype and node.param1 == 0 then
				-- abuse predicate so we can avoid iterating over it all later
				-- again -- this function is expensive enough already
				if (not lowermost) or where.y < lowermost.y then
					lowermost = where
				end

		local leaftype = treedef and treedef.leaves or nil
		if not leaftype then return false end

		local uppermost, lowermost
		local found_leaves = false

		local treemap, treenodes = amass(pos,function(node, where)

			if node.name == treetype and node.param1 == 0 then
				-- abuse predicate so we can avoid iterating over it all later
				-- again -- this function is expensive enough already
				if (not lowermost) or where.y < lowermost.y then
					lowermost = where
				end