function Block(lvl) {
  return {
    /* The block's parent */
    parent: null,
    /* Number of children */
    length: 0,
    /* Block's level */
    level: lvl,
    /* Lines of code to process */
    lines: [],
    /* Blocks with greater level */
    children: [],
    /* Add a block to the children collection */
    addChild: function (obj) {
      this.children.push(obj);
      obj.parent = this;
      ++this.length;
    },
  };
}
@class A block of lines of a given level.
@param {int} lvl The block's level.
@private