docs: def validate_message_dict(self, request_body):
          """With the JSON dict that will be sent to SendGrid's API,
              check the content for SendGrid API keys - throw exception if found.
  
             :param request_body: The JSON dict that will be sent to SendGrid's
                                  API.
             :type request_body: JSON serializable structure
             :raise ApiKeyIncludedException: If any content in request_body
                                             matches regex
          """
  
          # Handle string in edge-case
          if isinstance(request_body, str):
              self.validate_message_text(request_body)
  
          # Default param
          elif isinstance(request_body, dict):
  
              contents = request_body.get("content", list())
  
              for content in contents:
                  if content is not None:
                      if (content.get("type") == "text/html" or
                              isinstance(content.get("value"), str)):
                          message_text = content.get("value", "")
                          self.validate_message_text(message_text)