docs: def convert_to_feature_collection(self):
          """Convert data into a FeatureCollection if it is not already."""
          if self.data['type'] == 'FeatureCollection':
              return
          if not self.embed:
              raise ValueError(
                  'Data is not a FeatureCollection, but it should be to apply '
                  'style or highlight. Because `embed=False` it cannot be '
                  'converted into one.\nEither change your geojson data to a '
                  'FeatureCollection, set `embed=True` or disable styling.')
          # Catch case when GeoJSON is just a single Feature or a geometry.
          if 'geometry' not in self.data.keys():
              # Catch case when GeoJSON is just a geometry.
              self.data = {'type': 'Feature', 'geometry': self.data}
          self.data = {'type': 'FeatureCollection', 'features': [self.data]}