How to setup the default version on Ubuntu

• Check your python version
  

  ~$ python
  Python 3.2 (r32:88445, Mar 25 2011, 19:28:28) 
  [GCC 4.5.2] on linux2
  Type "help", "copyright", "credits" or "license" for more information.

• Mine is 3.2, what if I want to switch to default version 2.7
  

  which python
  /usr/bin/python 

•  Here is the command
  

  sudo mv /usr/bin/python /usr/bin/python32
  sudo ln -s /usr/bin/python2.7 /usr/bin/python