ast-stream

Abstract Syntax Tree as a stream

example:

```javascript
var map = require('map-stream');
var vfs = require('vinyl-fs');

var toAst = require('ast-stream')();

var astSrc = vfs.src(['./src/utils/*.js'])
.pipe(toAst)
.pipe(map(function (file, cb) {
var ast = file.ast;
// do something with ast, e.g. transform it
console.log(ast);
cb(null, file);
}));