code: func (c *Corpus) updateDeletes(deleteClaim schema.Claim) error {
  	target := c.br(deleteClaim.Target())
  	deleter := deleteClaim.Blob()
  	when, err := deleter.ClaimDate()
  	if err != nil {
  		return fmt.Errorf("Could not get date of delete claim %v: %v", deleteClaim, err)
  	}
  	del := deletion{
  		deleter: c.br(deleter.BlobRef()),
  		when:    when,
  	}
  	for _, v := range c.deletes[target] {
  		if v == del {
  			return nil
  		}
  	}
  	targetDeletions := append(c.deletes[target], del)
  	sort.Sort(sort.Reverse(byDeletionDate(targetDeletions)))
  	c.deletes[target] = targetDeletions
  	return nil
  }
docs: // updateDeletes updates the corpus deletes with the delete claim deleteClaim.
  // deleteClaim is trusted to be a valid delete Claim.