code: func (c *Corpus) IsDeleted(br blob.Ref) bool {
  	for _, v := range c.deletes[br] {
  		if !c.IsDeleted(v.deleter) {
  			return true
  		}
  	}
  	return false
  }
docs: // IsDeleted reports whether the provided blobref (of a permanode or claim) should be considered deleted.