code: def test_frequencies_controls_are_bounded(self):
      depth = 10
  
      def freq_scale_fn(x):
          return core.frequencies_sigmoid(
              x, depth=depth, hz_min=0.0, hz_max=8000.0
          )
  
      synthesizer = synths.Sinusoidal(
          n_samples=32000,
          sample_rate=16000,
          freq_scale_fn=freq_scale_fn,
      )
      batch_size = 3
      num_frames = 10
      n_partials = 100
      amps = tf.zeros(
          (batch_size, num_frames, n_partials), dtype=tf.float32
      )
      freqs = tf.linspace(-100.0, 100.0, n_partials)
      freqs = tf.tile(
          freqs[tf.newaxis, tf.newaxis, :, tf.newaxis],
          [batch_size, num_frames, 1, depth],
      )
  
      controls = synthesizer.get_controls(amps, freqs)
      freqs = controls["frequencies"]
      lt_nyquist = freqs <= 8000.0
      gt_zero = freqs >= 0.0
      both_conditions = np.logical_and(lt_nyquist, gt_zero)
  
      self.assertTrue(np.all(both_conditions))
  
file_path: ddsp/ddsp/synths_test.py
imports: from ddsp import core
  from ddsp import synths
  import numpy
  import tensorflow.compat.v2
label_desc: Use image node_id 2 for calling the SinusoidalTest obj's underlying member method code with example usage: obj.test_frequencies_controls_are_bounded() and returns: core