visitSetAccessor(tree) {
    this.visitAny(tree.name);
    this.visitList(tree.annotations);
  }
This is used to find something in a tree. Extend this class and override
the desired visit functions to find what you are looking for. When the tree
you are looking for is found set |this.found| to true. This will abort the
search of the remaining sub trees.

Does not search into nested functions.