old_contents: import adc
  
  # Pump rate in mL/s (4.3 L/min)
  _PUMP_RATE_ML_PER_SEC = 4300.0 / 60.0
  
  
  class Pump(object):
      """Wrapper for a Seaflo 12V water pump."""
  
      def __init__(self, adc, clock):
          """Creates a new Pump wrapper.
  
          Args:
              adc: ADC (analog to digital) interface to send digital signals to
                  pump.
              clock: A clock interface.
          """
          self._adc = adc
          self._clock = clock
  
      def pump_water(self, amount_ml):
          """Pumps the specified amount of water.
  
          Args:
              amount_ml: Amount of water to pump (in mL).
          """
          # TODO(JeetShetty): Implement this.
          if amount_ml == 0.0:
              return
          elif amount_ml < 0.0:
              raise ValueError('Cannot pump a negative amount of water')
          else:
              self._adc.write_pin(0, 1023)
          
              wait_time_seconds = amount_ml/_PUMP_RATE_ML_PER_SEC
              self._clock.wait(wait_time_seconds)
  
              self._adc.write_pin(0, 0)
  
          return
  
new_contents: import adc
  
  # Pump rate in mL/s (4.3 L/min)
  _PUMP_RATE_ML_PER_SEC = 4300.0 / 60.0
  
  
  class Pump(object):
      """Wrapper for a Seaflo 12V water pump."""
  
      def __init__(self, adc, clock):
          """Creates a new Pump wrapper.
  
          Args:
              adc: ADC (analog to digital) interface to send digital signals to
                  pump.
              clock: A clock interface.
          """
          self._adc = adc
          self._clock = clock
  
      def pump_water(self, amount_ml):
          """Pumps the specified amount of water.
  
          Args:
              amount_ml: Amount of water to pump (in mL).
          """
          
          if amount_ml == 0.0:
              return
          elif amount_ml < 0.0:
              raise ValueError('Cannot pump a negative amount of water')
          else:
              self._adc.write_pin(0, 1023)
          
              wait_time_seconds = amount_ml/_PUMP_RATE_ML_PER_SEC
              self._clock.wait(wait_time_seconds)
  
              self._adc.write_pin(0, 0)
  
          return
  
subject: Update pump.py