code: function(node, method) {
              while (node) {
                  node = node.previousSibling;
                  if ( Y.Dom._testElement(node, method) ) {
                      return node;
                  }
              }
              return null;
          }
docs: Returns the previous sibling that is an HTMLElement.
  For performance reasons, IDs are not accepted and argument validation omitted.
  Returns the nearest HTMLElement sibling if no method provided.
  @method getPreviousSiblingBy
  @param {HTMLElement} node The HTMLElement to use as the starting point
  @param {Function} method A boolean function used to test siblings
  that receives the sibling node being tested as its only argument
  @return {Object} HTMLElement or null if not found