old_contents: from rest_framework import serializers
  from .models import (
      CustomerUser,
      PhoneNumber,
      CreditCard,
      ShippingAddress
      )
  
  
  class PhoneNumberSerializer(serializers.ModelSerializer):
      class Meta:
          model = PhoneNumber
          fields = '__all__'
  
  
  class CustomerUserSerializer(serializers.ModelSerializer):
      class Meta:
          model = CustomerUser
          fields = '__all__'
  
  
  class CreditCardSerializer(serializers.ModelSerializer):
      class Meta:
          model = CreditCard
          fields = '__all__'
  
  
  class ShippingAddressSerializer(serializers.ModelSerializer):
      class Meta:
          model = ShippingAddress
          fields = '__all__'
  
new_contents: from rest_framework.authtoken.models import Token
  from rest_framework import serializers
  from .models import (
      CustomerUser,
      PhoneNumber,
      CreditCard,
      ShippingAddress
      )
  
  
  class PhoneNumberSerializer(serializers.ModelSerializer):
      class Meta:
          model = PhoneNumber
          fields = '__all__'
  
  
  class CustomerUserSerializerDefault(serializers.ModelSerializer):
      class Meta:
          model = CustomerUser
          fields = '__all__'
  
          extra_kwargs = {
              'password': {'write_only': True},
          }
  
  
  class CustomerUserSerializerPOST(serializers.ModelSerializer):
      class Meta:
          model = CustomerUser
          fields = ('pk', 'username', 'first_name', 'last_name',
                    'email', 'password')
  
          extra_kwargs = {
              'password': {'write_only': True},
          }
  
      def create(self, validated_data):
          user = CustomerUser(**validated_data)
          password = validated_data['password']
          user.set_password(password)
          user.save()
          token = Token.objects.create(user=user)
          token.save()
          return user
  
  
  class CreditCardSerializer(serializers.ModelSerializer):
      class Meta:
          model = CreditCard
          fields = '__all__'
  
  
  class ShippingAddressSerializer(serializers.ModelSerializer):
      class Meta:
          model = ShippingAddress
          fields = '__all__'
  
subject: Improve users serializers