Returns an observable sequence that is the result of invoking the selector on the source sequence, without sharing subscriptions.
This operator allows for a fluent style of writing queries that use the same sequence multiple times. There is an alias of
letBind for browsers older than IE 9.
Function): Selector function which can use the source sequence as many times as needed, without sharing subscriptions to the source sequence.
Observable): An observable sequence that contains the elements of a sequence produced by multicasting the source sequence within a selector function.