code: def sample_features(self, head_links, batch_num):
      pass
  
imports: import random
  import operator
  import numpy
  import itertools
  import operator
  import collections
  import abc
  import warnings
  from functools import reduce
  from tensorflow import keras
  from ..core.graph import StellarGraph, GraphSchema
  from ..data import SampledBreadthFirstWalk, SampledHeterogeneousBreadthFirstWalk, UniformRandomWalk, UnsupervisedSampler, DirectedBreadthFirstNeighbours
  from ..core.utils import is_real_iterable
  from .None import LinkSequence, OnDemandLinkSequence
  from ..random import SeededPerBatch
  from .base import Generator
label_desc: Use image node_id 2 for calling the BatchedLinkGenerator obj's underlying member method code with example usage: obj.sample_features(head_links, batch_num) without return types