Add the information of a compound variant

            This adds a compound dict to variant['compounds']

            Args:
                compound (dict): A compound dictionary

def add_compound(self, compound):
        """Add the information of a compound variant

            This adds a compound dict to variant['compounds']

            Args:
                compound (dict): A compound dictionary

        """
        logger.debug("Adding compound {0} to variant {1}".format(
            compound, self['variant_id']))
        self['compounds'].append(compound)