Dict literal now accepts expressions as keys. Key values are computed at evalutetion time and still must be integer or string

scan/token.go

@@ -136,3 +136,7 @@ func (tk *Token) ErrorExpectedGotStringWithPrefix(prefix, symbol, got string) (e
 	err = fmt.Errorf("[%d:%d] %s %s, got `%s`", tk.row, tk.col, prefix, symbol, got)
 	return
 }
+
+func (tk *Token) ErrorExpectedOneOfGot(expected ...Symbol) (err error) {
+	return tk.ErrorExpectedGotStringWithPrefix("expected one of ", SymListToString(expected, true), SymToString(tk.Sym))
+}