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.




$ octave
GNU Octave, version 3.0.2
Copyright (C) 2008 John W. Eaton and others.
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Octave was configured for "i586-mandriva-linux-gnu".
 
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octave:1> function concat(a,b,c)
> disp(strcat(a,c,c,b));
> endfunction
octave:2> concat("Rosetta","Code",":");
Rosetta::Code
octave:3>