Return length(meter) of the line

        :return: length(meter) of the line
        :rtype: float

def length(self):
        """
        Return length(meter) of the line

        :return: length(meter) of the line
        :rtype: float
        """
        return math.sqrt(
            (self.endpoint_a.northing - self.endpoint_b.northing) ** 2 +
            (self.endpoint_a.easting - self.endpoint_b.easting) ** 2
        )