old_contents: known_chains = {"STEEM" : {"chain_id" : "0" * int(256 / 4),
                             "core_symbol" : "STEEM",
                             "prefix" : "STM"},
                  }
  
new_contents: known_chains = {"STEEM" : {"chain_id" : "0" * int(256 / 4),
                             "core_symbol" : "STEEM",
                             "prefix" : "STM"},
                  "TEST" : {"chain_id" : "18dcf0a285365fc58b71f18b3d3fec954aa0c141c44e4e5cb4cf777b9eab274e",
                            "core_symbol" : "TESTS",
                            "prefix" : "TST"},
                  }
  
subject: Add Testnet chain