stream[@@can.getKeyValue](key)

can-reflect.getKeyValue will use this function to read the last emitted value or error by this stream.

Note, streams only have a value if onKeyValue is used to listen to changes. Use Kefir properties if you want to always be able to read a value.

The following creates a stream that immediately emits a value. When onKeyValue is used to listen to changes, it will immediately log 1. However, that value is preserved so getKeyValue can still be used:

import Kefir from "can-kefir";

const stream = Kefir.stream( function( emit ) {
    emit.value( 1 );
} );

canReflect.onKeyValue( stream, "value", function( newVal ) {
    console.log( "new value", newVal );
} ); // logs 1

canReflect.getKeyValue( stream, "value" ); //-> 1