src/index.js
function run (files, callback) {
  let self = this,
    i = 0;

  function next(err, files) {
    let mw = self.middleware[i++];

    if (mw) {
      mw(files, self, next);
    }
    else {
      callback(null, files);
    }

  };

  next(null, files);
}
function run (files, callback) {
  let self = this,
    i = 0;

  function next(err, files) {
    let mw = self.middleware[i++];

    if (mw) {
      mw(files, self, next);
    }
    else {
      callback(null, files);
    }

  };

  next(null, files);
}
function run ( files , callback ) { let self = this , i = 0 ; function next ( err , files ) { let mw = self . middleware [ i ++ ] ; if ( mw ) { mw ( files , self , next ) ; } else { callback ( null , files ) ; } } ; next ( null , files ) ; }
Run middleware pipeline
@param {Function} callback
Run middleware pipeline