type Result = variant { Ok : text; Err : text };
service : {
  batch_request : () -> (Result);
  get_block : (opt nat64) -> (Result);
  get_canister_addr : () -> (Result);
  get_eth_balance : (text) -> (Result);
  get_eth_gas_price : () -> (Result);
  send_eth : (text, nat64) -> (Result);
  send_token : (text, text, nat64) -> (Result);
  token_balance : (text, text) -> (Result);
}