From fd17e42c23ea27362c6d7312b5a3201a84e1321e Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Sun, 16 Aug 2020 09:45:34 -0700
Subject: [PATCH] Add about_point arg to Line.set_angle

---
 manimlib/mobject/geometry.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/manimlib/mobject/geometry.py b/manimlib/mobject/geometry.py
index b007318a..c175293f 100644
--- a/manimlib/mobject/geometry.py
+++ b/manimlib/mobject/geometry.py
@@ -468,11 +468,14 @@ class Line(TipableVMobject):
     def get_slope(self):
         return np.tan(self.get_angle())
 
-    def set_angle(self, angle):
+    def set_angle(self, angle, about_point=None):
+        if about_point is None:
+            about_point = self.get_start()
         self.rotate(
             angle - self.get_angle(),
-            about_point=self.get_start(),
+            about_point=about_point,
         )
+        return self
 
     def set_length(self, length):
         self.scale(length / self.get_length())