input: Write a function to generate a voltage signal with random noise given a frequency and amplitude in Hz and V respectively. The function should return the time array and the corresponding voltage signal array.
  assert generate_signal(250, 1)==([0.0, 0.001, 0.002, ..., 0.999, 1.0], [-0.0512, 0.9876, 0.0345, ..., 0.1234, -0.0987])
  assert generate_signal(500, 2)==([0.0, 0.001, 0.002, ..., 0.999, 1.0], [-0.0512, 1.9876, 0.0345, ..., 0.1234, -0.0987])
  assert generate_signal(100, 0.5)==([0.0, 0.001, 0.002, ..., 0.999, 1.0], [-0.0512, 0.4876, 0.0345, ..., 0.1234, -0.0987])
output: 
  import numpy as np
  
  def generate_signal(frequency, amplitude):
      time_array = np.arange(0, 1, 1/frequency)
      noise = np.random.normal(0, 0.1, len(time_array))
      voltage_signal = amplitude * np.sin(2 * np.pi * frequency * time_array) + noise
      return time_array, voltage_signal
  