code: def get_or_create_by_content(cls, name, content):
          
          new = False
          diagrams = cls.objects.filter(name=name)
          if diagrams:
              diagram = diagrams[0]
              if diagram.body != content:
                  new = True
          else:
              new = True
          if new:
              diagram = cls(name=name, body=content).save()
          return diagram, new
docs: if xml content updated, create a new entry for given wf name
          Args:
              name: name of wf
              content: xml content
  
          Returns (DiagramXML(), bool): A tuple with two members.
          (DiagramXML instance and True if it's new or False it's already exists