Converts object into a dictionary.

def _to_dict(self):
        """
        Converts object into a dictionary.
        """
        for i, tag in enumerate(self.tags):
            if tag in ("", None):
                self.tags.pop(i)

        data = {
            'name': self.name,
            'referenceId': self.reference_id,
            'shortDescription': self.short_description,
            'longDescription': self.long_description,
            'itemState': self.item_state,
            'linkURL': self.link_url,
            'linkText': self.link_text,
            'tags': self.tags,
            'economics': self.economics,
            'id': self.id,
            'end_date': _make_tstamp(self.end_date),
            'start_date': _make_tstamp(self.start_date)}
        if len(self.renditions) > 0:
            data['renditions'] = []
            for r in self.renditions:
                data['renditions'].append(r.to_dict())
        if len(self.metadata) > 0:
            data['customFields'] = {}
            for meta in self.metadata:
                data['customFields'][meta['key']] = meta['value']
        [data.pop(key) for key in data.keys() if data[key] == None]
        return data