code: function groupByProperty(objects) {
      const groupedObj = objects.reduce((accumulator, obj) => {
          const prop = Object.keys(obj)[0];
  
          accumulator[prop] = accumulator[prop] ? accumulator[prop].concat(obj) : [obj];
          return accumulator;
      }, {});
  
      return Object.keys(groupedObj).map(prop => groupedObj[prop]);
  }
docs: Group together valid rule configurations based on object properties
  
  e.g.:
  groupByProperty([
  {before: true},
  {before: false},
  {after: true},
  {after: false}
  ]);
  
  will return:
  [
  [{before: true}, {before: false}],
  [{after: true}, {after: false}]
  ]
  
  @param   {Object[]} objects Array of objects, each with one property/value pair
  @returns {Array[]}          Array of arrays of objects grouped by property