public String toString(final String sep){
  if (isEmpty()) {
    return StringUtilities.EMPTY;
  }
 else {
    final StringBuilder buffer=new StringBuilder();
    buffer.append(head);
    for (ImmutableList<A> l=tail; l.nonEmpty(); l=l.tail) {
      buffer.append(sep);
      buffer.append(l.head);
    }
    return buffer.toString();
  }
}

public String toString ( final String sep ) { if ( isEmpty ( ) ) { return StringUtilities . EMPTY ; } else { final StringBuilder buffer = new StringBuilder ( ) ; buffer . append ( head ) ; for ( ImmutableList < A > l = tail ; l . nonEmpty ( ) ; l = l . tail ) { buffer . append ( sep ) ; buffer . append ( l . head ) ; } return buffer . toString ( ) ; } }
form a string listing all elements with given separator character .
