!-- allows things like  'for j in wesnoth.get_sides({{"has_unit",{race="orc"}}}) do wesnoth.message(j.gold) end  '

--! Returns an iterator over teams matching a given side filter that can be used in a for-in loop.
function wesnoth.get_sides(cfg)
        local function f(s)
                local i = s.i
                local team
                repeat
                        i = i + 1
                        team = wesnoth.get_side(i)
                        if not team then return nil end
                until wesnoth.match_side(i,cfg)
                s.i = i
                return team
        end
        return f, { i = 0 }
end