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.




Windows PowerShell
Copyright (C) 2009 Microsoft Corporation. All rights reserved.
 
PS Home:\> function f ([string] $string1, [string] $string2, [string] $separator) {
>>     $string1 + $separator * 2 + $string2
>> }
>>
PS Home:\> f 'Rosetta' 'Code' ':'
Rosetta::Code
PS Home:\>