Adding keywords if a line starts with a certain word

[Robert Hicks]

I would like to add additional keywords if the first word or first 4 
characters of the statement is "snit".

snit::type dog {
    method {tail wag} {} {return "Wag, wag"}
    method {tail droop} {} {return "Droop, droop"}
}
Since "snit" is there then I would like to added "method" as a keyword.

Robert