code: @Nonnull
    public IMPLTYPE arg (@Nonnull final IJSExpression aExpr)
    {
      ValueEnforcer.notNull (aExpr, "Argument");
      m_aArgs.add (aExpr);
      return _thisAsT ();
    }
docs: Add an expression to this invocation's argument list
  
  @param aExpr
  Argument to add to argument list
  @return this