statement method
Implementation
Stmt statement() {
if (match([TokenType.FOR])) return forStatement();
if (match([TokenType.IF])) return ifStatement();
if (match([TokenType.PRINT])) return printStatement();
if (match([TokenType.RETURN])) return returnStatement();
if (match([TokenType.WHILE])) return whileStatement();
if (match([TokenType.LEFT_BRACE])) return Block(block());
return expressionStatement();
}