1  pragma solidity >=0.6.0;
 2  
 3  interface IOptionToken {
 4      function name() external view returns (string memory);
 5      function symbol() external view returns (string memory);
 6      function balanceOf(address account) external view returns (uint256);
 7      function transfer(address recipient, uint256 amount) external returns (bool);
 8      function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
 9      function burn(uint value) external;
10      function issue(address from, address to, uint value) external;
11      function burn(address owner, uint value) external;
12      function writtenVolume(address owner) external view returns (uint);
13      function uncoveredVolume(address owner) external view returns (uint);
14      function permit(
15          address owner, 
16          address spender,
17          uint256 value,
18          uint256 deadline,
19          uint8 v,
20          bytes32 r,
21          bytes32 s
22      ) external;
23  }