code: function addOutputs (next, outputs) {
    if (Array.isArray(outputs)) {
      outputs.forEach(key => {
        next[key] = next.bind(null, key);
      });
    }
  
    return next;
  }
docs: Add output paths to next function.
  
  Outputs takes from branches tree object.
  @example:
  var actions = [
  syncAction,
  [
  asyncAction,
  {
  custom1: [custom1SyncAction],
  custom2: [custom2SyncAction]
  }
  ]
  ];
  
  function asyncAction ({}, state, output) {
  if ( ... ) {
  output.custom1();
  } else {
  output.custom2();
  }
  }
  
  @param {Function} next
  @param {Array} outputs
  @returns {*}