module Lithic::Internal::Util

def normalized_headers(*headers)
  {}.merge(*headers.compact).to_h do |key, val|
    value =
      case val
      in Array
        val.filter_map { _1&.to_s&.strip }.join(", ")
      else
        val&.to_s&.strip
      end
    [key.downcase, value]
  end
end