code: function combineFilters(filters) {
    var allFilters, returnFn;
  
    allFilters = filters
      .filter(function(filter) {
        return defined(filter);
      })
      .reduce(function(filtersSoFar, thisFilter) {
        if (thisFilter._filterIndex) {
          // If a filter is an instance of this function just pull that filter's index into this one's.
          thisFilter._filterIndex.forEach(
            addToListUnique.bind(undefined, filtersSoFar)
          );
        } else {
          // Otherwise add it.
          addToListUnique(filtersSoFar, thisFilter);
        }
  
        return filtersSoFar;
      }, []);
  
    returnFn = function() {
      var outerArgs = arguments;
  
      return !allFilters.some(function(filter) {
        return !filter.apply(this, outerArgs);
      }, this);
    };
    returnFn._filterIndex = allFilters;
  
    return returnFn;
  }
docs: Combines a number of functions that return a boolean into a single function that executes all of them and returns
  true only if all them do. Maintains an set of filter functions, so if the same function is combined
  more than once, it is only executed one time. This means that it is also safe to call combineFilter on its own result
  to combine the result with another filter - the set of filters from the previous result will simply
  be merged into that of the new result so that only individual filter functions are executed.
  
  @param {Array} filters A number of functions to combine into one logical function.
  @returns {Function} The resulting function.