def _check_required_fields(self, fields=None, either_fields=None):
for (key, value) in fields.items():<EOL><INDENT>if not value:<EOL><INDENT>raise HSException("<STR_LIT>" % key)<EOL><DEDENT><DEDENT>if either_fields is not None:<EOL><INDENT>for field in either_fields:<EOL><INDENT>if not any(field.values()):<EOL><INDENT>raise HSException("<STR_LIT>" % "<STR_LIT:U+002CU+0020>".join(field.keys()))<EOL><DEDENT><DEDENT><DEDENT>
Check the values of the fields

        If no value found in `fields`, an exception will be raised.
        `either_fields` are the fields that one of them must have a value

        Raises:
            HSException: If no value found in at least one item of`fields`, or
                no value found in one of the items of `either_fields`

        Returns:
            None