input: def generate_noisy_signal(frequency: float, amplitude: float, duration: float, num_points: int) -> np.ndarray:
      """ Generate a voltage signal with random noise.
      >>> np.random.seed(42)
      >>> generate_noisy_signal(250, 1, 1, 1000)
      array([ 0.00323699,  0.28260797,  0.90137851, ...,  0.40875899, -0.50867231, -0.39856478])
      """
      t = np.linspace(0, duration, num_points)
      voltage_signal = amplitude * np.sin(2 * np.pi * frequency * t) + np.random.normal(0, 0.1, num_points)
      return voltage_signal
  
  import numpy as np
output:     t = np.linspace(0, duration, num_points)
      voltage_signal = amplitude * np.sin(2 * np.pi * frequency * t) + np.random.normal(0, 0.1, num_points)
      return voltage_signal