code: def validate(self, raise_unsupported=False):
          
          fields = set(self.keys())
          flattened_required_fields = set()
          required_errors = []
          for field in self.required_fields:
              found = False
              if isinstance(field, (list, tuple)):
                  # Check all alternatives
                  for real_f in field:
                      if real_f in fields:
                          flattened_required_fields.add(real_f)
                          found = True
              else:
                  flattened_required_fields.add(field)
                  if field in fields:
                      found = True
              if not found:
                  required_errors.append(field)
          unsupported_fields = fields - flattened_required_fields \
                  - set(self.optional_fields)
          if len(required_errors) or (raise_unsupported
                  and len(unsupported_fields)):
              raise exceptions.InvalidStructure("Missing or unsupported fields found",
                      required_fields=required_errors,
                      unsupported_fields=unsupported_fields)
docs: Checks if the Entry instance includes all the required fields of its
          type. If ``raise_unsupported`` is set to ``True`` it will also check
          for potentially unsupported types.
  
          If a problem is found, an InvalidStructure exception is raised.