dm_control: Import of refs/pull/442/head

PiperOrigin-RevId: 617978935
Change-Id: I566a0a9bdf42b50cce7512f73ba2e678035abcd5

Author: WangHanSolo

dm_control/mjcf/README.md

@@ -22,7 +22,7 @@ collision occurs.
 ```python
 from dm_control import mjcf
 
-class Arm(object):
+class Arm:
 
   def __init__(self, name):
     self.mjcf_model = mjcf.RootElement(model=name)
@@ -38,7 +38,7 @@ class Arm(object):
     self.forearm.add('geom', name='forearm', type='capsule',
                      pos=[0, 0, -0.15], size=[0.045, 0.15])
 
-class UpperBody(object):
+class UpperBody:
 
   def __init__(self):
     self.mjcf_model = mjcf.RootElement()
@@ -430,10 +430,10 @@ ensure that two models do not become subtly "incompatible". For example:
 
 ```python
 model_1 = mjcf.RootElement()
-model_1.compiler.angle = 'radians'
+model_1.compiler.angle = 'radian'
 
 model_2 = mjcf.RootElement()
-model_2.compiler.angle = 'degrees'
+model_2.compiler.angle = 'degree'
 
 model_1.attach(model_2)  # Error!
 ```
@@ -446,14 +446,14 @@ become problematic is:
 model_1 = mjcf.RootElement()
 
 model_2 = mjcf.RootElement()
-model_2.compiler.angle = 'degrees'
+model_2.compiler.angle = 'degree'
 
 model_1.attach(model_2)  # No error, but all angles in model_1 are now wrong!
 ```
 
 Here, `model_1` assumes MuJoCo's default angle unit of radians. Since it does
 not explicitly assign a value to `compiler.angle`, PyMJCF does not detect a
-conflict with `angle=degrees` in `model_2`. All angles in `model_1` are now
+conflict with `angle=degree` in `model_2`. All angles in `model_1` are now
 incorrectly interpreted as degrees.
 
 ### Elements outside of `<worldbody>`