Add an affiliation.

        Args:
            value (string): affiliation value
            curated_relation (bool): is relation curated
            record (dict): affiliation JSON reference

def add_affiliation(self, value, curated_relation=None, record=None):
        """Add an affiliation.

        Args:
            value (string): affiliation value
            curated_relation (bool): is relation curated
            record (dict): affiliation JSON reference
        """
        if value:
            affiliation = {
                'value': value
            }
            if record:
                affiliation['record'] = record
            if curated_relation is not None:
                affiliation['curated_relation'] = curated_relation
            self._ensure_list_field('affiliations', affiliation)