Grant a privilege on a database to a user.

        :param privilege: the privilege to grant, one of 'read', 'write'
            or 'all'. The string is case-insensitive
        :type privilege: str
        :param database: the database to grant the privilege on
        :type database: str
        :param username: the username to grant the privilege to
        :type username: str

def grant_privilege(self, privilege, database, username):
        """Grant a privilege on a database to a user.

        :param privilege: the privilege to grant, one of 'read', 'write'
            or 'all'. The string is case-insensitive
        :type privilege: str
        :param database: the database to grant the privilege on
        :type database: str
        :param username: the username to grant the privilege to
        :type username: str
        """
        text = "GRANT {0} ON {1} TO {2}".format(privilege,
                                                quote_ident(database),
                                                quote_ident(username))
        self.query(text, method="POST")