validate that we have the same order as the existing & same dtype

def validate_attr(self, append):
        """validate that we have the same order as the existing & same dtype"""
        if append:
            existing_fields = getattr(self.attrs, self.kind_attr, None)
            if (existing_fields is not None and
                    existing_fields != list(self.values)):
                raise ValueError("appended items do not match existing items"
                                 " in table!")

            existing_dtype = getattr(self.attrs, self.dtype_attr, None)
            if (existing_dtype is not None and
                    existing_dtype != self.dtype):
                raise ValueError("appended items dtype do not match existing "
                                 "items dtype in table!")