code: def find_stages(document):
      
      names = []
      if 'pipeline' in document:
          for entry in document['pipeline']:
              # each entry is dictionary with one key only
              key, _ = list(entry.items())[0]
              if key.startswith("stage("):
                  names.append(key.replace('stage(', '').replace(')', ''))
      return names
docs: Find  **stages** in document.
  
      Args:
          document (dict): validated spline document loaded from a yaml file.
  
      Returns:
          list: stages as a part of the spline document or an empty list if not given.
  
      >>> find_stages({'pipeline': [{'stage(Prepare)':1}, {'stage(Build)':1}, {'stage(Deploy)':2}]})
      ['Prepare', 'Build', 'Deploy']