code: def num_inducing(self) -> Optional[tf.Tensor]:
      return tf.shape(self.Z)[0]
  
imports: import abc
  from typing import Optional
  import tensorflow
  import tensorflow_probability
  from check_shapes import Shape, check_shapes
  from deprecated import deprecated
  from ..base import Module, Parameter, TensorData, TensorType
  from ..utilities import positive
label_desc: Use image node_id 2 for calling the InducingPointsBase obj's underlying member method code with example usage: obj.num_inducing() and returns: tf