_prune(nodeArrays) {
    for (let i = 0; i < nodeArrays.length; i++) {
      let nodes = nodeArrays[i];
      for (let j = 0; j < nodes.length; j++) {
        this._removeNode(nodes[j]);
      }
    }
  }
Removes the nodes from consideration in any additional matches.

@private

@param {Node[][]} nodeArrays