function keyframePriority(previousKeyframe, keyframe, nextKeyframe, traversal) {
  const keyframeDifference = Math.min(
    Math.abs(keyframe - previousKeyframe),
    Math.abs(keyframe - nextKeyframe),
  );
  const maxKeyframeDifference = Math.max(
    previousKeyframe,
    traversal._keyframeCount - nextKeyframe - 1,
    1,
  );
  const keyframeFactor = Math.pow(
    1.0 - keyframeDifference / maxKeyframeDifference,
    4.0,
  );
  const binaryTreeFactor = Math.exp(
    -traversal._binaryTreeKeyframeWeighting[keyframe],
  );
  return CesiumMath.lerp(
    binaryTreeFactor,
    keyframeFactor,
    0.15 + 0.85 * keyframeFactor,
  );
}
Compute a priority for a keyframe node.

@private
@param {number} previousKeyframe
@param {number} keyframe
@param {number} nextKeyframe
@param {VoxelTraversal} traversal
@returns {number} The computed priority