parser

type Element struct {
	Type     ElementType    // type of the element
	Tokens   []*lexer.Token // tokens associated with this element
	Children *list.List     // list of sub elements
}

type ElementType struct {
	Name     string            // Name of the ekement
	TokTypes []lexer.TokenType // types of allowed tokens
	NTokens  int               // number of tokens managed
}