lastIndexOf method
override
    Returns the last index of element in this list.
Searches the list backwards from index start to 0.
The first time an object o is encountered so that o == element,
the index of o is returned.
List<String> notes = ['do', 're', 'mi', 're'];
notes.lastIndexOf('re', 2); // 1
If start is not provided, this method searches from the end of the
list./Returns
notes.lastIndexOf('re');  // 3
Returns -1 if element is not found.
notes.lastIndexOf('fa');  // -1
Implementation
int lastIndexOf(Object element, [int start]) {
  if (start == null || start >= this.length) start = this.length - 1;
  for (int i = start; i >= 0; i--) {
    if (this[i] == element) return i;
  }
  return -1;
}