(not implemented) Finds the first value within a collection that passes a test.
This method is defined by an ECMAScript 6 proposal and documented on MDN.
Version 1 of collections supports a deprecated alternative to find(callback,
thisp), find(value, equals, start).
In version 2, this method has been renamed findValue.
(not implemented) Finds the last value within a collection that passes a test, searching from the right.
(not implemented) Finds the first value within a collection that passes a test. Finds the first index within a collection that passes a test.
Finds the first equivalent value.