[texhax] \if... \else... \fi command

[Rodolfo Medina]

Hi, everyone.

I'm a plain TeX user. I wrote:

\newtoks\filename
\filename={file6}

Then I want to write an `if... \else...\fi' command 
which says `yes' if \filename={file6} and `no' in any other case.

I tried with

\if\filename file6 Yes \else No \fi
 
but it goes on saying `no', whereas I expect it should say `yes'. 
What should the right syntax be? Can anyone help?

Thanks in advance,
                Rodolfo