updateUser(parent, args, ctx, info){
        const user = users.find((user) => user.id === args.id)
        if(!user){
            throw new Error('User does not exist!')
        }

        if(typeof args.email === 'string'){
            const isEmailExists = db.users.some((user) => user.email === args.email)
            if(isEmailExists){
                throw new Error('Email already Taken')
            }
            user.email = args.email
        }

        if(typeof args.name === 'string'){
            user.name = args.name
        }

        if(typeof args.age !== 'undefined'){
            user.age = args.age
        }

        return user

    }