https://github.com/clearmatics/asset-token/blob/master/contracts/AssetToken.sol
https://github.com/enjin/erc-1155/tree/master/contracts
https://github.com/enjin/erc-1155/blob/master/contracts/ERC1155.sol
https://github.com/clearmatics/asset-token/blob/master/contracts/AssetToken.sol
https://github.com/enjin/erc-1155/tree/master/contracts
https://github.com/enjin/erc-1155/blob/master/contracts/ERC1155.sol