code: def at_least_3d(x):
      """Optionally adds time, batch, then channel dimension."""
      x = x[tf.newaxis] if not x.shape else x
      x = x[tf.newaxis, :] if len(x.shape) == 1 else x
      x = x[:, :, tf.newaxis] if len(x.shape) == 2 else x
      return x
  
imports: import ddsp
  from ddsp.training import nn
  import gin
  import tensorflow
label_desc: Use image node_id 1 for calling a global function with example usage: at_least_3d(x) and returns: x