# File lib/active_merchant/billing/gateways/paypal/paypal_common_api.rb, line 63
      def initialize(options = {})
        requires!(options, :login, :password)
        
        headers = {'X-PP-AUTHORIZATION' => options.delete(:auth_signature), 'X-PAYPAL-MESSAGE-PROTOCOL' => 'SOAP11'} if options[:auth_signature]
        @options = {
          :pem => pem_file,
          :signature => signature,
          :headers => headers || {}
        }.update(options)

        
        if @options[:pem].blank? && @options[:signature].blank?
          raise ArgumentError, "An API Certificate or API Signature is required to make requests to PayPal" 
        end
        
        super
      end