text: const { Readable } = require("stream");
  const strom = require("stromjs");
  
  const source1 = new Readable({ read() {} });
  const source2 = new Readable({ read() {} });
  strom.merge(source1, source2).pipe(process.stdout);
  source1.push("a1 ");
  setTimeout(() => source2.push("c3 "), 10);
  setTimeout(() => source1.push("b2 "), 20);
  setTimeout(() => source2.push("d4 "), 30);
  setTimeout(() => source1.push(null), 40);
  setTimeout(() => source2.push(null), 50);
  