#     assert [1..10].count(1)	== 1
	#     assert [1..10].count(0)	== 0
	redef fun count(item)
	do
		if has(item) then
			return 1
		else
			return 0
		end
	end

	redef fun count(e)
	do
		mutex.lock
		var r = real_collection.count(e)
		mutex.unlock
		return r
	end

	redef fun count(an_item)
	do
		if item == an_item then
			return 1
		else
			return 0
		end
	end

	redef fun count(item)
	do
		var res = 0
		var i = 0
		var l = length
		while i < l do
			if self[i] == item then res += 1
			i += 1
		end
		return res
	end

	redef fun count(k) do if self.has(k) then return 1 else return 0

	# O(n)
	redef fun count(item)
	do
		var nb = 0
		for i in self.map._items do if i.second == item then nb += 1
		return nb
	end

	redef fun count(k) do if self.has(k) then return 1 else return 0

	redef fun count(item)
	do
		var nb = 0
		var c = self.map._first_item
		while c != null do
			if c._value == item then nb += 1
			c = c._next_item
		end
		return nb
	end

	# Only 0 or 1
	redef fun count(item)
	do
		if has(item) then
			return 1
		else
			return 0
		end
	end

	redef fun count(e)
	do
		var nb = 0
		var node = _head
		while node != null do
			if node.item != e then nb += 1
			node = node.next
		end
		return nb
	end