Flask query mysql

excuse me, after flask query mysql, plus limit offset, how to determine whether the return value is found or not?

r = Lines.query.filter(Lines.jp.like("%%")).limit(10).offset(10)

print (r) returns sql string
print (r is None) is always False
print (type (r)) returns < class" flask_sqlalchemy.BaseQuery" >


for i in r:
    print(i)
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1becbab-3129b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1becbab-3129b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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