can you combine unions and interfaces in graphql code example

Example 1: can you do a join() in js without the commas

arr.join("")

Example 2: doest all the methos in interface need to implement c#

You have two choices:

- implement every method required by the interface
or
- declare the missing methods abstract in your class. This forces you
to declare your class abstract and, as a result, forces you to
subclass the class (and implement the missing methods) before you
can create any objects.