diff --git a/parser.go b/parser.go
index 9868dec..f23a009 100644
--- a/parser.go
+++ b/parser.go
@@ -72,11 +72,11 @@ func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 				if subTree.root.symbol() == SymIdentifier {
 					args = append(args, subTree.root)
 				} else {
-					err = tk.Errorf("exptected identifier, got %q", subTree.root)
+					err = tk.ErrorExpectedGotString("param-name", subTree.root.String())
 				}
 			} else if itemExpected {
 				prev := scanner.Previous()
-				err = prev.Errorf("expected function parameter, got %q", prev)
+				err = prev.ErrorExpectedGot("function-param", prev)
 				break
 			}
 		} else {
@@ -87,18 +87,20 @@ func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 	}
 
 	if err == nil && lastSym != SymClosedRound {
-		err = tk.Errorf("unterminated function parameters list")
+		err = tk.ErrorExpectedGot(")")
 	}
 	if err == nil {
 		tk = scanner.Next()
 		if tk.Sym == SymOpenBrace {
 			body, err = self.parseGeneral(scanner, true, true, SymClosedBrace)
+		} else {
+			err = tk.ErrorExpectedGot("{")
 		}
 	}
 	if err == nil {
 		// TODO Check arguments
 		if scanner.Previous().Sym != SymClosedBrace {
-			err = scanner.Previous().Errorf("not properly terminated function body")
+			err = scanner.Previous().ErrorExpectedGot("}")
 		} else {
 			tk = scanner.makeValueToken(SymExpression, "", body)
 			tree = newFuncDefTerm(tk, args)
@@ -118,7 +120,7 @@ func (self *parser) parseList(scanner *scanner, allowVarRef bool) (subtree *term
 				args = append(args, subTree.root)
 			} else if itemExpected {
 				prev := scanner.Previous()
-				err = prev.Errorf("expected list item, got %q", prev)
+				err = prev.ErrorExpectedGot("list-item")
 				break
 			}
 		} else {
@@ -130,7 +132,7 @@ func (self *parser) parseList(scanner *scanner, allowVarRef bool) (subtree *term
 	if err == nil {
 		// TODO Check arguments
 		if lastSym != SymClosedSquare {
-			err = scanner.Previous().Errorf("unterminate items list")
+			err = scanner.Previous().ErrorExpectedGot("]")
 		} else {
 			subtree = newListTerm(args)
 		}
@@ -150,7 +152,7 @@ func (self *parser) parseIterDef(scanner *scanner, allowVarRef bool) (subtree *t
 				args = append(args, subTree.root)
 			} else if itemExpected {
 				prev := scanner.Previous()
-				err = prev.Errorf("expected iterator argument, got %q", prev)
+				err = prev.ErrorExpectedGot("iterator-param")
 				break
 			}
 		} else {
@@ -162,7 +164,7 @@ func (self *parser) parseIterDef(scanner *scanner, allowVarRef bool) (subtree *t
 	if err == nil {
 		// TODO Check arguments
 		if lastSym != SymClosedRound {
-			err = scanner.Previous().Errorf("unterminate iterator param list")
+			err = scanner.Previous().ErrorExpectedGot(")")
 		} else {
 			subtree = newIteratorTerm(tk, args)
 		}
@@ -182,12 +184,13 @@ func (self *parser) parseDictKey(scanner *scanner, allowVarRef bool) (key any, e
 	if tk.Sym == SymInteger || tk.Sym == SymString {
 		tkSep := scanner.Next()
 		if tkSep.Sym != SymColon {
-			err = tkSep.Errorf("expected \":\", got %q", tkSep)
+			err = tkSep.ErrorExpectedGot(":")
 		} else {
 			key = tk.Value
 		}
 	} else {
-		err = tk.Errorf("expected dictionary key or closed brace, got %q", tk)
+		// err = tk.Errorf("expected dictionary key or closed brace, got %q", tk)
+		err = tk.ErrorExpectedGot("dictionary-key or }")
 	}
 	return
 }
@@ -205,7 +208,7 @@ func (self *parser) parseDictionary(scanner *scanner, allowVarRef bool) (subtree
 			tk := scanner.Previous()
 			lastSym = tk.Sym
 			if itemExpected {
-				err = tk.Errorf("expected dictionary key, got %q", tk)
+				err = tk.ErrorExpectedGot("dictionary-key")
 			}
 			break
 		}
@@ -214,7 +217,7 @@ func (self *parser) parseDictionary(scanner *scanner, allowVarRef bool) (subtree
 				args[key] = subTree.root
 			} else if key != nil {
 				prev := scanner.Previous()
-				err = prev.Errorf("expected dictionary value, got %q", prev)
+				err = prev.ErrorExpectedGot("dictionary-value")
 				break
 			}
 		} else {
@@ -226,7 +229,7 @@ func (self *parser) parseDictionary(scanner *scanner, allowVarRef bool) (subtree
 	if err == nil {
 		// TODO Check arguments
 		if lastSym != SymClosedBrace {
-			err = scanner.Previous().Errorf("unterminated dictionary")
+			err = scanner.Previous().ErrorExpectedGot("}")
 		} else {
 			subtree = newDictTerm(args)
 		}
@@ -260,7 +263,7 @@ func (self *parser) parseSelectorCase(scanner *scanner, allowVarRef bool, defaul
 			return
 		}
 	} else {
-		err = tk.Errorf("selector-case expected, got %q", tk.source)
+		err = tk.ErrorExpectedGot("{")
 	}
 
 	if err == nil {
diff --git a/scanner.go b/scanner.go
index 8a6ba93..bc6d8ef 100644
--- a/scanner.go
+++ b/scanner.go
@@ -160,6 +160,12 @@ func (self *scanner) fetchNextToken() (tk *Token) {
 			//} else if next == '/' {
 			if next, _ := self.peek(); next == '/' {
 				tk = self.moveOn(SymDotSlash, ch, next)
+			} else if next == '.' {
+				if next1, _ := self.peek(); next1 == '.' {
+					tk = self.moveOn(SymTripleDot, ch, next, next1)
+				} else {
+					tk = self.moveOn(SymDoubleDot, ch, next)
+				}
 			} else {
 				tk = self.makeToken(SymDot, ch)
 			}
diff --git a/symbol.go b/symbol.go
index 0ccf089..7c930a5 100644
--- a/symbol.go
+++ b/symbol.go
@@ -65,6 +65,8 @@ const (
 	SymDollarRound                       //  54: '$('
 	SymOpenClosedRound                   //  55: '()'
 	SymDoubleDollar                      //  56: '$$'
+	SymDoubleDot                         //  57: '..'
+	SymTripleDot                         //  58: '...'
 	SymChangeSign
 	SymUnchangeSign
 	SymIdentifier
diff --git a/token.go b/token.go
index c515e35..2fadb27 100644
--- a/token.go
+++ b/token.go
@@ -46,7 +46,7 @@ func NewValueToken(row, col int, sym Symbol, source string, value any) *Token {
 
 func NewErrorToken(row, col int, err error) *Token {
 	if err == io.EOF {
-		return NewToken(row, col, SymEos, "")
+		return NewToken(row, col, SymEos, "<EOF>")
 	}
 	return NewValueToken(row, col, SymError, fmt.Sprintf("[%d:%d]", row, col), err)
 }
@@ -81,3 +81,13 @@ func (self *Token) Errors(msg string) (err error) {
 	err = fmt.Errorf("[%d:%d] %v", self.row, self.col, msg)
 	return
 }
+
+func (self *Token) ErrorExpectedGot(symbol string) (err error) {
+	err = fmt.Errorf("[%d:%d] expected %q, got %q", self.row, self.col, symbol, self)
+	return
+}
+
+func (self *Token) ErrorExpectedGotString(symbol, got string) (err error) {
+	err = fmt.Errorf("[%d:%d] expected %q, got %q", self.row, self.col, symbol, got)
+	return
+}