'Associates a route table with a specific subnet.
:type route_table_id: str
:param route_table_id: The ID of the route table to associate.
:type subnet_id: str
:param subnet_id: The ID of the subnet to associate with.
:type dry_run: bool
:param dry_run: Set to True if the operation should not actually run.
:rtype: str
:return: The ID of the association created'

def associate_route_table(self, route_table_id, subnet_id, dry_run=False):

    params = {'RouteTableId': route_table_id, 'SubnetId': subnet_id}
    if dry_run:
        params['DryRun'] = 'true'
    result = self.get_object('AssociateRouteTable', params, ResultSet)
    return result.associationId
