code: func claimPtrsAttrValue(claims []*camtypes.Claim, attr string, at time.Time, signerFilter SignerRefSet) string {
  	return claimsIntfAttrValue(claimPtrSlice(claims), attr, at, signerFilter)
  }
docs: // claimPtrsAttrValue returns the value of attr from claims,
  // or the empty string if not found.
  // Claims should be sorted by claim.Date.