gistfile1.js

// say i have a pipeline of streams:
a.pipe(b).pipe(c).pipe(d)

// and these process objects, like
{ foo: "hello", bar: 55 }

// say i have a magical number processing stream, like "square" which only takes + emits numbers.
square.write(5) // emits 25

// And i want to set it up between b and c above. so like
a.pipe(b).pipe(square).pipe(c).pipe(d)

// but this doesn't work because that stream only takes numbers.
// how can i "wrap" the nums stream, to invoke its square magic
// only with the number part of an object?