series (PDF::Reader::RegisterReceiver)

    # File lib/pdf/reader/register_receiver.rb, line 52
        def series(*methods)
          return nil if methods.empty?

          indexes = (0..(callbacks.size-1-methods.size))
          method_indexes = (0..(methods.size-1))
          match = nil

          indexes.each do |idx|
            count = methods.size
            method_indexes.each do |midx|
              count -= 1 if callbacks[idx+midx][:name] == methods[midx]
            end
            match = idx and break if count == 0
          end

          if match
            return callbacks[match, methods.size]
          else
            return nil
          end
        end