def METHOD_NAME(
    self,
    grant_id: str, state: GrantState,
    hb_interval_sec: int, last_hb_ts: int,
    low_frequency_hz: int = 3500,
    high_frequency_hz: int = 3700,
) -> ActiveModeCbsdBuilder:
    grant = Grant(
        id=grant_id,
        state=state,
        heartbeat_interval_sec=hb_interval_sec,
        last_heartbeat_timestamp=last_hb_ts,
        low_frequency_hz=low_frequency_hz,
        high_frequency_hz=high_frequency_hz,
    )
    self.grants.append(grant)
    return self