// Declarations = Declaration*
    private void parseDeclarations() {
        while (currentToken == Token.INT || currentToken == Token.BOOLEAN)
            parseDeclaration();
    }

    // Declaration = Type Identifiers ";"
    private void parseDeclaration() {
        parseType();
        parseIdentifiers();
        accept(Token.SEMICOLON);
    }

    // Identifiers = Identifier ("," Identifier)*
    private void parseIdentifiers() {
        parseIdentifier();
        while (currentToken.kind == Token.SEMICOLOR){
        accept(Token.COMA);
        parseIdentifier();
        }
    }

    // Type = "int" | "boolean"
    private void parseType() {
        if (currentToken.kind == Token.INT)
            accept("int");
        else if (currentToken.kind == Token.BOOLEAN)
            accept ("boolean");
        else new Error("Syntax error: A suitable message.", currentToken.line);
    }

    // Statements = Statement*
    private void parseStatements() {
        while (currentToken.kind == Token.SEMICOLON || currentToken.kind ==  Token.LBRACE || currentToken.kind == Token.IF || currentToken.kind == Token.WHILE)
            parseStatement();
    }

    // Statement = ";" | Block | Assignment | IfStatement | WhileStatement
    private void parseStatement() {
        if (currentToken.kind == Token.SEMICOLON)
            expectIt();
        else if (currentToken.kind == Token.LBRACE) {
            parseBlock();
        }
        else if (currentToken.kind == Token.IDENTIFIER) {
            parseAssignment();
        }
        else if (currentToken.kind == Token.IF) {
            parseIfStatement();
        }
        else if (currentToken.kind == Token.WHILE) {
            parseWhileStatement();
        }
        else new Error("Expeting ;, left brace, etc.", currentToken.line);
    }


private void parseBlock() {
        accept (Token.LBRACE);
        parseStatements();
        accept (Token.RBRACE);
    }

    // Assignment = Identifier "=" Expression ";"
    /*

     */
    private void parseAssignment() {
         parseIdentifier();
         accept (Token.ASSIGN);
         parseExpression();
         accept (Token.SEMICOLON);
    }