code: func (bb *Builder) SetClaimDate(t time.Time) *Builder {
  	if !bb.IsClaimType() {
  		// This is a little gross, using panic here, but I
  		// don't want all callers to check errors.  This is
  		// really a programming error, not a runtime error
  		// that would arise from e.g. random user data.
  		panic("SetClaimDate called on non-claim *Builder; camliType=" + bb.Type())
  	}
  	bb.m["claimDate"] = RFC3339FromTime(t)
  	return bb
  }
docs: // SetClaimDate sets the "claimDate" on a claim.
  // It is a fatal error to call SetClaimDate if the Map isn't of Type "claim".