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_xyxy(self):
      """
      [xmin, ymin, xmax, ymax]
      """
      if self.multipolygon.area != 0:
          _, voc_bbox = get_bbox_from_shapely(self.multipolygon)
          # fix coord by slice box
          if self.slice_bbox:
              minx = self.slice_bbox[0]
              miny = self.slice_bbox[1]
              voc_bbox[0] = voc_bbox[0] - minx
              voc_bbox[2] = voc_bbox[2] - minx
              voc_bbox[1] = voc_bbox[1] - miny
              voc_bbox[3] = voc_bbox[3] - miny
      else:
          voc_bbox = []
      return voc_bbox
  
imports: from typing import List
  from shapely.geometry import CAP_STYLE, JOIN_STYLE, MultiPolygon, Polygon, box
label_desc: Use image node_id 12 for calling the ShapelyAnnotation obj's underlying member method code with example usage: obj.to_xyxy() and returns: voc_bbox