Token not defined error in player class

// this is the player class who creates an instance of the Token class

class Player {
    constructor(name, id, color, active = false) {
        this.name = name;
        this.id = id;
        this.color = color;
        this.active = active;
        this.tokens = this.createTokens(21);
    }

   /**
     * Creates token objects for player
     * @param   {integer}   num - Number of token objects to be created
     * @return  {array}     tokens - an arary of new token objects
     */
    createTokens(num) {
        const tokens = [];

        for (let i = 0; i < num; i++) {
            let token = new Token(i, this);
            tokens.push(token);
        }

        return tokens;
    }
}