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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def sine_wave(frequency):
 """Emit a sine wave at the given frequency."""

  xs = tf.reshape(tf.range(_samples(), dtype=tf.float32), [1, _samples(), 1])
  ts = xs / FLAGS.sample_rate
  return tf.sin(2 * math.pi * frequency * ts)