# File lib/faraday/adapter/typhoeus.rb, line 52
      def parse_response_headers(header_string)
        return {} unless header_string && !header_string.empty?
        Hash[*header_string.split(/\r\n/).
          tap  { |a|      a.shift           }. # drop the HTTP status line
          map! { |h|      h.split(/:\s+/,2) }. # split key and value
          map! { |(k, v)| [k.downcase, v]   }.flatten!]
      end