code: def validate(self, syntax_only=False):
          
          self.packer_cmd = self.packer.validate
  
          self._add_opt('-syntax-only' if syntax_only else None)
          self._append_base_arguments()
          self._add_opt(self.packerfile)
  
          # as sh raises an exception rather than return a value when execution
          # fails we create an object to return the exception and the validation
          # state
          try:
              validation = self.packer_cmd()
              validation.succeeded = validation.exit_code == 0
              validation.error = None
          except Exception as ex:
              validation = ValidationObject()
              validation.succeeded = False
              validation.failed = True
              validation.error = ex.message
          return validation
docs: Validates a Packer Template file (`packer validate`)
  
          If the validation failed, an `sh` exception will be raised.
          :param bool syntax_only: Whether to validate the syntax only
          without validating the configuration itself.