instruction: since 207 days ago, list the daily maximum heartrate of patient 007-15837.
response: SELECT MAX(vitalperiodic.heartrate) FROM vitalperiodic WHERE vitalperiodic.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '007-15837')) AND NOT vitalperiodic.heartrate IS NULL AND DATETIME(vitalperiodic.observationtime) >= DATETIME(CURRENT_TIME(), '-207 day') GROUP BY STRFTIME('%y-%m-%d', vitalperiodic.observationtime)