def setExtendedInfo(name, value):
    """Add extension data to the transaction.

        :param text name:
          is the text (unicode) name of the extension property to set

        :param value:
          must be picklable and json serializable

        Multiple calls may be made to set multiple extension
        properties, provided the names are distinct.

        Storages record the extension data, as meta-data, when a transaction
        commits.

        A storage may impose a limit on the size of extension data; behavior
        is undefined if such a limit is exceeded (for example, a storage may
        raise an exception, or remove `<name, value>` pairs).
        """
