code: function selector(str) {
          var elems = [];
  
          each(str.split(/\s*,\s*/), function(s) {
              var m = s.match(/([#.])(\w+)/);
              if (m === null) {
                  throw Error('Supports only simple single #ID or .CLASS selector.');
              }
  
              if (m[1]) {
                  var elem = document.getElementById(m[2]);
  
                  if (elem) {
                      elems.push(elem);
                  }
              }
  
              elems = elems.concat(getElementsByClassName(str));
          });
  
          return elems;
      }
docs: Simple selector.
  
  @param {String} str #ID or .CLASS
  
  @returns {Array}