python - Not able to get the resources attached with route table -

i using python aws infrastructure automation. need resources attached route table api given

ec2  = boto3.resource('ec2') route_table_association = ec2.routetableassociation('rtb-**********') response=route_table_association.get_available_subresources() 

here return type of response giving me empty list time. , response=route_table_association.delete() gives exception

an error occurred (invalidassociationid.notfound) when calling `disassociateroutetable operation: association id 'rtb-*********' not exist.` 

but route tebale exist , attached subnet explicitly

the id required routetableassociationid i.e. rtbassoc-xxxxxx , not route table id.

routetableassociationid inside describe_route_tables response json 'associations' element.

{     'routetables': [         {             'routetableid': 'string',             'vpcid': 'string',             'routes': [                 {....}             ],             'associations': [                 {                     'routetableassociationid': 'string',                     'routetableid': 'string',                     'subnetid': 'string',                     'main': true|false                 },             ], ..... }