title: split string in to 2 based on last occurrence of a separator
body: <p>I would like to know if there is any built in function in python to break the string in to 2 parts, based on the last occurrence of a separator.</p>
  
  <p>for eg:
  consider the string "a b c,d,e,f" , after the split over separator ",", i want the output as</p>
  
  <p>"a b c,d,e" and "f". </p>
  
  <p>I know how to manipulate the string to get the desired output, but i want to know if there is any in built function in python.</p>