def normalize_sensor_port port
      raw_port = Integer(port) - 1
      raise ArgumentError.new("Sensor ports must be 1 through 4: got #{port.inspect}") unless [0,1,2,3].include? raw_port
      byte(raw_port)
    end
def normalize_sensor_port port
      raw_port = Integer(port) - 1
      raise ArgumentError.new("Sensor ports must be 1 through 4: got #{port.inspect}") unless [0,1,2,3].include? raw_port
      byte(raw_port)
    end
Converts a port symbol into the appropriate byte().

 @param [Fixnum] port It should be 1, 2, 3, or 4 (which correspond to the markings on the brick )
 @return [UnsignedByte] The corresponding byte for the port.