input: Write a python function to create a CloudFormation template with an SNS topic using the given structure.
  assert create_sns_template("MySNSTopic") == {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Resources": {
          "MySNSTopic": {
              "Type": "AWS::SNS::Topic",
              "Properties": {
                  "TopicName": "MySNSTopic"
              }
          }
      }
  }
  assert create_sns_template("TestTopic") == {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Resources": {
          "TestTopic": {
              "Type": "AWS::SNS::Topic",
              "Properties": {
                  "TopicName": "TestTopic"
              }
          }
      }
  }
output: def create_sns_template(topic_name):
      return {
          "AWSTemplateFormatVersion": "2010-09-09",
          "Resources": {
              topic_name: {
                  "Type": "AWS::SNS::Topic",
                  "Properties": {
                      "TopicName": topic_name
                  }
              }
          }
      }