class_docstr: Abstract generator class.
      
docstr: Load annotations for all images in group.
          
code: def load_annotations_group(self, group):
      """Load annotations for all images in group."""
      annotations_group = [
          self.load_annotations(image_index) for image_index in group
      ]
      for annotations in annotations_group:
          assert isinstance(
              annotations, dict
          ), "'load_annotations' should return a list of dictionaries, received: {}".format(
              type(annotations)
          )
          assert (
              "labels" in annotations
          ), "'load_annotations' should return a list of dictionaries that contain 'labels' and 'bboxes'."
          assert (
              "bboxes" in annotations
          ), "'load_annotations' should return a list of dictionaries that contain 'labels' and 'bboxes'."
  
      return annotations_group
  
imports: import numpy
  import random
  import warnings
  from tensorflow import keras
  from ..utils.anchors import anchor_targets_bbox, anchors_for_shape, guess_shapes
  from ..utils.config import parse_anchor_parameters, parse_pyramid_levels
  from ..utils.image import TransformParameters, adjust_transform_for_image, apply_transform, preprocess_image, resize_image
  from ..utils.transform import transform_aabb
label_desc: Use image node_id 13 for calling the Generator obj's underlying member method code with example usage: obj.load_annotations_group(group) and returns: annotations_group