code: public static <T> List<T> leftShift(List<T> self, T value) {
          return (List<T>) leftShift((Collection<T>) self, value);
      }
docs: Overloads the left shift operator to provide an easy way to append
  objects to a List.
  <pre class="groovyTestCase">def list = [1,2]
  list &lt;&lt; 3
  assert list == [1,2,3]</pre>
  
  @param self  a List
  @param value an Object to be added to the List.
  @return same List, after the value was added to it.
  @since 2.4.0