input: Write a function to generate a voltage signal with random noise based on a given frequency and amplitude. The function should return the generated signal.
  def generate_voltage_signal(freq, amplitude):
      import numpy as np
      t = np.linspace(0, 1, 1000)
      voltage_signal = np.sin(2*np.pi*freq*t) + np.random.normal(0, 0.1, 1000)
      return voltage_signal
  
  assert np.shape(generate_voltage_signal(250, 1)) == (1000,)
  assert np.all(np.abs(np.sin(2*np.pi*250*np.linspace(0, 1, 1000)) - generate_voltage_signal(250, 1) + np.random.normal(0, 0.1, 1000)) < 0.1)
output: def generate_voltage_signal(freq, amplitude):
      import numpy as np
      t = np.linspace(0, 1, 1000)
      voltage_signal = np.sin(2*np.pi*freq*t) + np.random.normal(0, 0.1, 1000)
      return voltage_signal