code: public static <T> Seq<T> of(Collection<T> c) {
          if (N.isNullOrEmpty(c)) {
              return EMPTY;
          }
  
          return new Seq<>(c);
      }
docs: The returned <code>Seq</code> and the specified <code>Collection</code> are backed by the same data.
  Any changes to one will appear in the other.
  
  @param c
  @return