Special UTF8 characters as methods in ruby

[Six]

I'm trying to figure out how to define as a method a special math
symbol:

def – num # Not seeing the square root symbol after def here?
Wouldn't surprise me.
Math.sqrt num
end

-- but ruby gives me the error:
:3: Invalid char `\342' in expression
:3: Invalid char `\210' in expression
:3: Invalid char `\232' in expression
Program exited.

I know there is a way to do this and I've looked for a couple days but
can't seem to re-find it. Anyone ever gotten this to work; if so, how?

 

[Six]

Nevermind, figured it out.

Note to self:

$KCODE = "UTF-8"
ruby -Ku script_with_funky_chars

Pardon the bother.