npx hardhat compile failed.

[philsong]

➜ cover-core-v1 git:(main) ✗ npx hardhat compile --show-stack-traces
Compiling 25 files with 0.7.3
contracts/ProtocolFactory.sol:15:1: TypeError: Contract "ProtocolFactory" should be marked as abstract.
contract ProtocolFactory is IProtocolFactory, Ownable {
^ (Relevant source part starts here and spans across multiple lines).
contracts/interfaces/IProtocolFactory.sol:41:3: Missing implementation:
function assignClaimManager(address _address) external returns (bool);
^--------------------------------------------------------------------^

Error HH600: Compilation failed

HardhatError: HH600: Compilation failed
at SimpleTaskDefinition.config_env_1.subtask.addParam.addParam.setAction [as action] (/Users/phil/DeFi/cover-core-v1/node_modules/hardhat/src/builtin-tasks/compile.ts:751:15)
at process._tickCallback (internal/process/next_tick.js:68:7)