old_contents: module.exports = (sequelize, DataTypes) => {
    const Group = sequelize.define('Group', {
      name: {
        type: DataTypes.STRING,
        allowNull: false,
        unique: true
      },
      description: {
        type: DataTypes.STRING,
        allowNull: false,
      }
    }, {
      classMethods: {
        associate: (models) => {
          Group.hasMany(models.Message, {
            foreignKey: 'groupId',
            as: 'groupMesages',
          });
          Group.belongsToMany(models.User, {
            as: 'Groups',
            foreignKey: 'userId',
            through: 'UserGroup',
          });
        },
      },
    });
    return Group;
  };
  
new_contents: module.exports = (sequelize, DataTypes) => {
    const Group = sequelize.define('Group', {
      name: {
        type: DataTypes.STRING,
        allowNull: false,
      },
      description: {
        type: DataTypes.STRING,
        allowNull: false,
      }
    }, {
      classMethods: {
        associate: (models) => {
          Group.hasMany(models.Message, {
            foreignKey: 'groupId',
            as: 'groupMesages',
          });
          Group.belongsToMany(models.User, {
            as: 'Groups',
            foreignKey: 'userId',
            through: 'UserGroup',
          });
        },
      },
    });
    return Group;
  };
  
subject: Remove unique property