def create_post(publication, opts)
      response = @client.post "publications/#{publication['id']}/posts",
                              build_request_with(opts)
      Medium::Client.validate response
    end
def create_post(publication, opts)
      response = @client.post "publications/#{publication['id']}/posts",
                              build_request_with(opts)
      Medium::Client.validate response
    end
Creates a post in a publication on behalf of the authenticated user.

 @param publication [Publication] A publication object.
 @param opts [Hash] A hash of options to use when creating a post. The opts
   hash requires the keys: `:title`, `:content_format`, and `:content`. The
   following keys are optional: `:tags`, `:canonical_url`,
   `:publish_status`, and `:license`
 @return [Hash] The response is a Post object within a data envelope.
   Example response:
   ```
   HTTP/1.1 201 OK
   Content-Type: application/json; charset=utf-8
   {
     "data": {
       "id": "e6f36a",
       "title": "Liverpool FC",
       "authorId": "5303d74c64f66366f00cb9b2a94f3251bf5",
       "tags": ["football", "sport", "Liverpool"],
       "url": "https://medium.com/@majelbstoat/liverpool-fc-e6f36a",
       "canonicalUrl": "http://jamietalbot.com/posts/liverpool-fc",
       "publishStatus": "public",
       "publishedAt": 1442286338435,
       "license": "all-rights-reserved",
       "licenseUrl": "https://medium.com/policy/9db0094a1e0f",
       "publicationId": "e3ef7f020bd"
     }
   }
   ```