class_docstr: Creates ShapelyAnnotation (as shapely MultiPolygon).
  Can convert this instance annotation to various formats.
docstr: [xmin, ymin, xmax, ymax]
docstr_tok: ["[","xmin",",","ymin",",","xmax",",","ymax","]"]
code: def to_voc_bbox(self):
      """
      [xmin, ymin, xmax, ymax]
      """
      return self.to_xyxy()
  
imports: from typing import List
  from shapely.geometry import CAP_STYLE, JOIN_STYLE, MultiPolygon, Polygon, box
label_desc: Use image node_id 13 for calling the ShapelyAnnotation obj's underlying member method code with example usage: obj.to_voc_bbox() and returns: self