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GameLevel.tsx

import React from 'react';

type Entity = {
  name: string;
  strength: number;
};

type Props = {
  player: Entity;
  enemy: Entity;
};

export const GameLevelStateless = ({ player, enemy }: Props) => (
  <main>{player.strength - enemy.strength}</main>
);

type State = {
  score: number;
};

export class GameLevelClass extends React.Component<Props, State> {
  state = {
    score: 5,
  };

  render() {
    return <GameLevelStateless {...this.props} />;
  }
}

export default GameLevelClass;