def METHOD_NAME(self, statement_id):
    _validate_uuid(statement_id)
    try:
        # Statement exists
        statement = self.statements[statement_id]
        if statement.status != "STARTED":
            raise ValidationException(
                "Could not cancel a query that is already in %s state with ID: %s"
                % (statement.status, statement_id)
            )
        statement.status = "ABORTED"
        self.statements[statement_id] = statement
    except KeyError:
        # Statement does not exist.
        raise ResourceNotFoundException()
    return True