code: public static SecurityManager createSecurityManager(SystemMail systemMail, Main main) throws IllegalAccessException {
          if (!exists) {
              SecurityManager securityManager = new SecurityManager(systemMail, main);
              exists = true;
              return  securityManager;
          }
          throw new IllegalAccessException("Cannot create more than one instance of IzouSecurityManager");
      }
docs: Creates a SecurityManager. There can only be one single SecurityManager, so calling this method twice
  will cause an illegal access exception.
  
  @param systemMail the system mail object in order to send e-mails to owner in case of emergency
  @param main a reference to the main instance
  @return a SecurityManager from Izou
  @throws IllegalAccessException thrown if this method is called more than once