class_docstr: Creates ShapelyAnnotation (as shapely MultiPolygon).
  Can convert this instance annotation to various formats.
code: def get_convex_hull_shapely_annotation(self):
      shapely_multipolygon = MultiPolygon(
          [self.multipolygon.convex_hull]
      )
      shapely_annotation = ShapelyAnnotation(shapely_multipolygon)
      return shapely_annotation
  
imports: from typing import List
  from shapely.geometry import CAP_STYLE, JOIN_STYLE, MultiPolygon, Polygon, box
label_desc: Use image node_id 14 for calling the ShapelyAnnotation obj's underlying member method code with example usage: obj.get_convex_hull_shapely_annotation() and returns: shapely_annotation