code: @NullSafe
    @Override
    public boolean accept(File pathname) {
      return (pathname != null && pathname.canExecute() == executable);
    }
docs: Accepts or rejects the given {@link File} based on whether it is executable or not.  This method is null-safe
  and guards against null {@link File} references.
  
  @param pathname the {@link File} to evaluate.
  @return a boolean value indicating whether the executable {@link File} is accepted or rejected.
  @see org.cp.elements.lang.Filter#accept(Object)
  @see java.io.FileFilter#accept(File)
  @see java.io.File#canExecute()