-- Unlock rare metal technologies if the player has already mined rare metals.
for _, force in pairs(game.forces) do
  for _, surface in pairs(game.surfaces) do
    local item_stats = force.get_item_production_statistics(surface)
    if item_stats.get_output_count("kr-rare-metal-ore") > 0 then
      force.technologies["kr-rare-metal-mining"].researched = true
      force.technologies["kr-rare-metal-processing"].researched = true
      break
    end
  end
end