Many language implementations come with an interactive mode.

This is a command-line interpreter that reads lines from the user and evaluates these lines as statements or expressions.

An interactive mode may also be known as a command mode,   a read-eval-print loop (REPL),   or a shell.



Task

Show how to start this mode.

Then, as a small example of its use, interactively create a function of two strings and a separator that returns the strings separated by two concatenated instances of the separator   (the 3rd argument).



Example

             f('Rosetta',  'Code',  ':')   

should return

             'Rosetta::Code'               



Note

This task is   not   about creating your own interactive mode.




C:\>scala
Welcome to Scala version 2.8.0.r21356-b20100407020120 (Java HotSpot(TM) Client V
M, Java 1.6.0_05).
Type in expressions to have them evaluated.
Type :help for more information.
 
scala> "rosetta"
res0: java.lang.String = rosetta