code: function partition(collection, fn) {
    var result = { lhs: [], rhs: [] };
    _.forEach(collection, function(value) {
      if (fn(value)) {
        result.lhs.push(value);
      } else {
        result.rhs.push(value);
      }
    });
    return result;
  }
docs: /*
  Partition a collection into two groups: `lhs` and `rhs`. If the supplied
  function returns true for an entry it goes into `lhs`. Otherwise it goes
  into `rhs.