code: def merge(self, node):
          
                  
          self.feature += node.feature;
          
          for child in node.successors:
              child.parent = self;
              self.successors.append(child);
docs: !
          @brief Merge non-leaf node to the current.
          
          @param[in] node (non_leaf_node): Non-leaf node that should be merged with current.