import { of } from 'rxjs' ; export function play ( ... args ) { const numbers = [ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ] ; /**
     * To double the odd integers and sum them ...
     * chain with array operators
     */ const result = numbers . filter ( i => i % 2 === 1 ) . map ( i => i * 2 ) . reduce ( ( acc , curr ) => acc + curr , 0 ) ; return of ( result ) ; }