old_contents: from rest_framework import serializers
  
  class RefugeeCampSerializer(serializers.Serializer):
      city = serializers.CharField()
      postcode = serializers.CharField()
      street = serializers.CharField()
      streetnumber = serializers.CharField()
  
  class SimpleOfferSerializer(serializers.Serializer):
      title = serializers.CharField()
      description = serializers.CharField()
  
      city = serializers.CharField()
      telephone = serializers.CharField()
      email = serializers.EmailField()
  
new_contents: from rest_framework import serializers
  from api.models import SimpleOffer
  
  class RefugeeCampSerializer(serializers.Serializer):
      city = serializers.CharField()
      postcode = serializers.CharField()
      street = serializers.CharField()
      streetnumber = serializers.CharField()
  
  class SimpleOfferSerializer(serializers.Serializer):
      title = serializers.CharField()
      description = serializers.CharField()
  
      city = serializers.CharField()
      telephone = serializers.CharField()
      email = serializers.EmailField()
  
      def create(self, validated_data):
          """
          Create and return a new `Snippet` instance, given the validated data.
          """
          return SimpleOffer.objects.create(**validated_data)
  
      def update(self, instance, validated_data):
          """
          Update and return an existing `Snippet` instance, given the validated data.
          """
          instance.title = validated_data.get('title', instance.title)
          instance.description = validated_data.get('description', instance.description)
          instance.city = validated_data.get('city', instance.city)
          instance.telephone = validated_data.get('telephone', instance.telephone)
          instance.email = validated_data.get('email', instance.email)
          instance.save()
          return instance
      
subject: Implement SimpleOffer saving