Method arg

basex-core/src/main/java/org/basex/query/expr/Expr.java:396–399

Returns the specified argument/operand of an expression (function, list, etc.). @param a index of argument @return argument or Empty#UNDEFINED if argument is undefined

(final int a)

   * @return argument or {@link Empty#UNDEFINED} if argument is undefined
   */
  public Expr arg(final int a) {
    final Expr[] args = args();
    return args != null && a < args.length ? args[a] : Empty.UNDEFINED;
  }

  /**
   * Optimizes an expression for positional access.