Title: Select an expression with side-effect
Goal: Generalize the function `f/2' by selecting the expression `exit("Some message")', the a new parameter is `Exit'.
Parameters: [{file,"gen20.erl"},{posrange,{77,96}},{varname,"Exit"}].
Documentation: The selected expression has side-effect, so a fun expression without parameters is created and added to the argument list of the function calls. There is not any variable with the name `Exit', so it is possible to introduce a new pattern and replace the selected expression with an application. The name of the application is the new variable name.  
