<INITIAL> "->" => (Tokens.ARROW (yypos, yypos + size yytext));
<INITIAL> "=>" => (Tokens.DARROW (yypos, yypos + size yytext));
+<INITIAL> "<-" => (Tokens.LARROW (yypos, yypos + size yytext));
<INITIAL> "=" => (Tokens.EQ (yypos, yypos + size yytext));
<INITIAL> "," => (Tokens.COMMA (yypos, yypos + size yytext));