fcn parseRuleSet(lines){
   if(vm.numArgs>1) lines=vm.arglist;  // lines or object
   ks:=L(); vs:=L();
   foreach line in (lines){
      if(line[0]=="#") continue;	// nuke <comment>
      pattern,replacement:=line.replace("\t"," ")
         .split(" -> ",1).apply("strip");
      ks.append(pattern); vs.append(replacement);
   }
   return(ks,vs);
}

fcn markov(text,rules){
   ks,vs:=rules; eks:=ks.enumerate();
   do{ go:=False;
      foreach n,k in (eks){
	 if (Void!=text.find(k)){
	    if (Void==(v:=vs[n])) return(text);
	    if (v[0,1]==".") v=v[1,*] else go=True;
	    text=text.replace(k,v,1);
	    break;  // restart after every rule application, unless terminating
	 }
      }
   }while(go);
   text
}