code: def get_field_from_args_or_session(config, args, field_name):
      
      rez = getattr(args, field_name, None)
      #type(rez) can be int in case of wallet-index, so we cannot make simply if(rez)
      if (rez != None):
          return rez
      rez = config.get_session_field("default_%s"%field_name, exception_if_not_found=False)
      if (rez):
          return rez
      raise Exception("Fail to get default_%s from config, should specify %s via --%s parameter"%(field_name, field_name, field_name.replace("_","-")))
docs: We try to get field_name from diffent sources:
      The order of priorioty is following:
      - command line argument (--<field_name>)
      - current session configuration (default_<filed_name>)