function blockgame.get_keys (tab)
	local keyset = {}
	local n = 0
	for key, value in pairs(tab) do
		n = n + 1
		keyset[n] = key
	end
	return keyset
end

function blockgame.shallow_copy_table (tab)
	local result = {}
	for key, value in pairs(tab) do
		result[key] = value
	end
	return result
end

function blockgame.naive_deep_copy (tab)
	local result = {}
	for key, value in pairs(tab) do
		if type(value) == "table" then
			result[key] = blockgame.naive_deep_copy(value)
		else
			result[key] = value
		end
	end
	return result
end

function blockgame.shuffle (tab)
	local keys = blockgame.get_keys(tab)
	local result = {}
	while #keys > 0 do
		local index = math.random(1, #keys)
		local key = table.remove(keys, index)
		table.insert(result, tab[key])
	end
	return result
end

function blockgame.any (tab, check)
	for key, value in pairs(tab) do
		if check(value, key, tab) then return true end
	end
	return false
end

function blockgame.every (tab, check)
	for key, value in pairs(tab) do
		if not check(value, key, tab) then return false end
	end
	return true
end

function blockgame.underride (tab, template)
	local tab = tab or {}
	local result = blockgame.naive_deep_copy(template)
	for key, value in pairs(tab) do
		if type(value) == "table" then
			result[key] = blockgame.underride(value, template[key] or {})
		else
			result[key] = value
		end
	end
	return result
end