title: Save data with pyfirmata analog read
body: <p>I am using a potentiometer to get a value between 0 and 1. I am able to print it in the console but the type of the data is 'NoneType'. Would it be possible to change this data type to a 'float' so that I can save it in a variable?
  Here is my code for now:</p>
  <pre><code>from pyfirmata import Arduino
  import pyfirmata
  import time
  port = &quot;COM3&quot;
  board = Arduino(port)
  List = []
  pin = board.get_pin('a:0:i')
  it = pyfirmata.util.Iterator(board)
  it.start()
  print(&quot;Start reading&quot;)
  for i in range(3):
      analog_value = pin.read()
      print(analog_value)
      List.append(analog_value)
      time.sleep(0.1)
      del List[0]
  print(List)
  </code></pre>