code: function markLoneBlock() {
              if (loneBlocks.length === 0) {
                  return;
              }
  
              const block = context.getAncestors().pop();
  
              if (loneBlocks[loneBlocks.length - 1] === block) {
                  loneBlocks.pop();
              }
          }
docs: Checks the enclosing block of the current node for block-level bindings,
  and "marks it" as valid if any.
  @returns {void}