input: Write a function to generate a voltage signal with random noise using a Python script. The function should take the frequency and amplitude of the signal as inputs and return the generated voltage signal.
  assert generate_voltage_signal(250, 1).shape == (1000,)
  assert all(-1.1 <= val <= 1.1 for val in generate_voltage_signal(250, 1))
  assert not all(val == generate_voltage_signal(250, 1)[0] for val in generate_voltage_signal(250, 1))
  assert generate_voltage_signal(500, 2).shape == (1000,)
  assert all(-2.1 <= val <= 2.1 for val in generate_voltage_signal(500, 2))
  assert not all(val == generate_voltage_signal(500, 2)[0] for val in generate_voltage_signal(500, 2))
output: import numpy as np
  
  def generate_voltage_signal(frequency, amplitude):
      t = np.linspace(0, 0.004, 1000)
      signal = amplitude * np.sin(2 * np.pi * frequency * t)
      noise = np.random.normal(0, 0.1, 1000)
      return signal + noise