🚀 go-pugleaf

I know this was requested once but I never saw an answer or summary.  
Anyway,  I am working on a small logo interpreter for a math (that's
right) class and I would like to see a grammar (yacc compatible would
be good) that someone else has done.  I'm not looking to steal someone
elses code but would like to see how it should be done.  I know there 
is really no standard but what would you consider to be the standard
core of commands.  Thanks in advance,

Jeff Sandfort

P.S.  I'll post a summary of anything I get.