def __i(self, other, func):
        """Process input other with input func.

        :param ModelElement(s) other: other ModelElement(s) to process.
        :param func: function to apply on a ModelElement.
        :return: self.
        :raise: TypeError if other is not a ModelElement(s)."""

        if isinstance(other, type(self)):
            other = tuple(other)

        elif isinstance(other, self.__contenttype__):
            other = (other, )

        for melt in list(other):
            if not isinstance(melt, self.__contenttype__):
                raise TypeError('Wrong element {0}'.format(melt))

            else:
                func(melt)

        return self
Process input other with input func.

        :param ModelElement(s) other: other ModelElement(s) to process.
        :param func: function to apply on a ModelElement.
        :return: self.
        :raise: TypeError if other is not a ModelElement(s).