code: def parse_pin(name_str):
      
      if len(name_str) < 1:
          raise ValueError("Expecting pin name to be at least 4 charcters.")
      if name_str[0] != 'P':
          raise ValueError("Expecting pin name to start with P")
      pin_str = name_str[1:].split('/')[0]
      if not pin_str.isdigit():
          raise ValueError("Expecting numeric pin number.")
      return int(pin_str)
docs: Parses a string and returns a pin-num.