pdf.create(html [, options]).toBuffer(callback)
pdf.create(html [, options]).toStream(callback)
pdf.create(html [, options]).toFile([filename, ]callback)

// for backwards compatibility
pdf.create(html [, options], callback)

  pdf = require('html-pdf')
  pdf.create(html).toFile(filepath, function(err, res){
    console.log(res.filename);
  });

  pdf.create(html).toStream(filepath, function(err, stream){
    steam.pipe(fs.createWriteStream('./foo.pdf'));
  });

  pdf.create(html).toBuffer(filepath, function(err, buffer){
    console.log('This is a buffer:', Buffer.isBuffer(buffer));
  });