def create_lease_object_from_idx(self, idx):
return self.create_lease_object_from_subnet(<EOL>self._subnet_template.format(idx)<EOL>)<EOL>
Create a lease from self._subnet_template and put idx as its third
octet.

Args:
    idx (str): The value of the third octet

Returns:
    Lease: Lease object which represents the requested subnet.

Raises:
    LagoSubnetLeaseOutOfRangeException: If the resultant subnet is
    malformed or out of the range of the store.