code: function BlockMeta(hash, height, time) {
    if (!(this instanceof BlockMeta))
      return new BlockMeta(hash, height, time);
  
    this.hash = hash || encoding.NULL_HASH;
    this.height = height != null ? height : -1;
    this.time = time || 0;
  }
docs: Block Meta
  @constructor
  @param {Hash} hash
  @param {Number} height
  @param {Number} time