do

local function dict()
    local self = {length = 0, dd = {}};
    local set = function(k, v)
        self.dd[k] = v;
        self.length = self.length + 1;
    end
    local del = function(k)
        self.dd[k] = nil;
        if self.length > 0 then
            self.length = self.length - 1;
        end
    end
    local get = function(k)
        return self.dd[k];
    end
    local len = function()
        return self.length;
    end
    return
    {
        set = set,
        del = del,
        get = get,
        len = len
    }
end

dictionary = {
    dict = dict,
}

end