def add_atomic_unset(document)
      document.flagged_for_destroy = true
      (delayed_atomic_unsets[document.association_name.to_s] ||= []).push(document)
    end
def add_atomic_unset(document)
      document.flagged_for_destroy = true
      (delayed_atomic_unsets[document.association_name.to_s] ||= []).push(document)
    end
Add an atomic unset for the document.

 @example Add an atomic unset.
   document.add_atomic_unset(doc)

 @param [ Document ] document The child document.

 @return [ Array<Document> ] The children.

 @since 3.0.0