docs: def add_variant(self, variant):
          """Add a variant to the variant collection
          
              If the variant exists we update the count else we insert a new variant object.
          
              Args:
                  variant (dict): A variant dictionary
          
          """
          LOG.debug("Upserting variant: {0}".format(variant.get('_id')))
          
          update = self._get_update(variant)
          
          message = self.db.variant.update_one(
              {'_id': variant['_id']},
              update,
              upsert=True
          )
          if message.modified_count == 1:
              LOG.debug("Variant %s was updated", variant.get('_id'))
          else:
              LOG.debug("Variant was added to database for first time")
          return