A converter that binds an index in a list to the selected item's value as a viewModel property.
When the getter is called, returns the item at the passed in index (which should be a can-compute from the provided list.
When the setter is called, takes the selected item and finds the index from the list and passes that to set the compute’s value.
<input value:bind="selected-to-index(~index, people)" />
A compute that will be two-way bound to the value.
index must be a can-compute so that its value can be set on user actions.