树莓派4B的ROS，出现missing: PY_EM错误

按照大神文章安装树莓派4B的ROS，出现missing: PY_EM错误

https://blog.youkuaiyun.com/weixin_42587961/article/details/102229510

sudo ./src/catkin/bin/catkin_make_isolated --install -DCMAKE_BUILD_TYPE=Release --install-space /opt/ros/kinetic

出现错误：

-- Could NOT find PY_em (missing: PY_EM) 
CMake Error at cmake/empy.cmake:30 (message):
  Unable to find either executable 'empy' or Python module 'em'...  try
  installing the package 'python-empy'

需要安装python的empy

pip install empy