sympy.geometry.line.Segment.length

        Examples
        ========

        >>> from sympy import Point, Polygon
        >>> p1, p2, p3, p4 = map(Point, [(0, 0), (1, 0), (5, 1), (0, 1)])
        >>> poly = Polygon(p1, p2, p3, p4)
        >>> poly.perimeter
        sqrt(17) + 7
        r