'The direction vector of the LinearEntity.
Returns
p : a Point; the ray from the origin to this point is the
direction of `self`
Examples
>>> from sympy.geometry import Line
>>> a, b = (1, 1), (1, 3)
>>> Line(a, b).direction
Point2D(0, 2)
>>> Line(b, a).direction
Point2D(0, -2)
This can be reported so the distance from the origin is 1:
>>> Line(b, a).direction.unit
Point2D(0, -1)
See Also
sympy.geometry.point.Point.unit'

@property
def direction(self):

    return (self.p2 - self.p1)
