human
Solve the following python programming problem given the following code:
def VerifyOrCreate(self, client, callback, verify_only = False) : 
    'Verifies the schema if it exists or creates it if not.
    Verification checks existing tables match the schema definition,
    warns of vestigial tables, and creates any tables which are
    missing.

    Vestigial tables may be deleted by specifying the --delete_vestigial
    command line flag.

    On completion, invokes callback with a list of verified table schemas.
    ' 
    def _OnDescribeTable(table, verify_cb, result) : 
        'Verifies the table description in schema matches the
      table in the database.
      ' 
        if verify_only : 
            verify_cb ((table.name, result)) 
            return 
assert isinstance (result, db_client.DescribeTableResult), result 
        if options.options.verify_provisioning : 
            if (table.read_units != result.schema.read_units) : 
                logging.warning ('%s: read units mismatch %d != %d', table.name, table.read_units, result.schema.read_units) 
if (table.write_units != result.schema.write_units) : 
                logging.warning ('%s: write units mismatch %d != %d', table.name, table.write_units, result.schema.write_units) 
assert (table.hash_key_schema == result.schema.hash_key_schema), ('%s: hash key schema mismatch %r != %r' % (table.name, table.hash_key_schema, result.schema.hash_key_schema)) 
        assert (table.range_key_schema == result.schema.range_key_schema), ('%s: range key schema mismatch %r != %r' % (table.name, table.range_key_schema, result.schema.range_key_schema)) 
        assert (result.schema.status in ['CREATING', 'ACTIVE']), ('%s: table status invalid: %s' % (table.name, result.schema.status)) 
        if (result.schema.status == 'CREATING') : 
            logging.info (('table %s still in CREATING state...waiting 1s' % table.name)) 
            client.AddTimeout (1.0, partial (_VerifyTable, table, verify_cb)) 
            return 
else : 
            logging.debug (('verified table %s' % table.name)) 
verify_cb ((table.name, result))...

    
    

    Fix the buggy line: client.ListTables (callback = client)
assistant
#Here is Python code to fix the buggy line: client.

client.ListTables (callback = def _OnListTables()