Add Table to XMLBIF.

        Return
        ---------------
        dict: dict of type {variable: table tag}

        Examples
        -------
        >>> writer = XMLBIFWriter(model)
        >>> writer.get_values()
        {'dog-out': <Element TABLE at 0x7f240726f3c8>,
         'light-on': <Element TABLE at 0x7f240726f488>,
         'bowel-problem': <Element TABLE at 0x7f240726f388>,
         'family-out': <Element TABLE at 0x7f240726f408>,
         'hear-bark': <Element TABLE at 0x7f240726f448>}

def get_values(self):
        """
        Add Table to XMLBIF.

        Return
        ---------------
        dict: dict of type {variable: table tag}

        Examples
        -------
        >>> writer = XMLBIFWriter(model)
        >>> writer.get_values()
        {'dog-out': <Element TABLE at 0x7f240726f3c8>,
         'light-on': <Element TABLE at 0x7f240726f488>,
         'bowel-problem': <Element TABLE at 0x7f240726f388>,
         'family-out': <Element TABLE at 0x7f240726f408>,
         'hear-bark': <Element TABLE at 0x7f240726f448>}
        """
        cpds = self.model.get_cpds()
        definition_tag = self.definition
        table_tag = {}
        for cpd in cpds:
            table_tag[cpd.variable] = etree.SubElement(definition_tag[cpd.variable], "TABLE")
            table_tag[cpd.variable].text = ''
            for val in cpd.get_values().ravel(order="F"):
                table_tag[cpd.variable].text += str(val) + ' '

        return table_tag