Fully-qualified name of this variable.

        Example:
        ``projects/my-project/configs/my-config/variables/my-var``

        :rtype: str
        :returns: The full name based on config and variable names.

        :raises: :class:`ValueError` if the variable is missing a name.

def full_name(self):
        """Fully-qualified name of this variable.

        Example:
        ``projects/my-project/configs/my-config/variables/my-var``

        :rtype: str
        :returns: The full name based on config and variable names.

        :raises: :class:`ValueError` if the variable is missing a name.
        """
        if not self.name:
            raise ValueError("Missing variable name.")
        return "%s/variables/%s" % (self.config.full_name, self.name)