We live in the Haute Vienne , France, and today we found a very small, thin all black snake, except for two bright yellow patches, one each side behind it's head. The belly was paler than the back. It was so thin it could have been a young snake. the head was large in relation to it's body diameter. Don't think it was a ring-necked snake as it's head was big, it was not yellow underneath and it was not a complete yellow ring around it's neck. Any ideas please?