# File lib/pdf/reader/register_receiver.rb, line 73
    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