new_contents: class CellInfo(object):
  
      def __init__(self, content_type, cell_type):
          self._content_type = content_type
          self._cell_type = cell_type
  
      @property
      def content_type(self):
          return self._content_type
  
      @property
      def cell_type(self):
          return self._cell_type
  
  
  class ContentType:
      USER_KEYWORD = object()
      LIBRARY_KEYWORD = object()
      VARIABLE = object()
      STRING = object()
      EMPTY = object()
  
  class CellType:
      MANDATORY = object()
      OPTIONAL = object()
      UNKNOWN = object()
      ERROR = object()
      MANDATORY_EMPTY = object()
subject: Add cellinfo