docs: def digest_content(self, rule):
          """
          Walk on rule content tokens to return a dict of properties.
  
          This is pretty naive and will choke/fail on everything that is more
          evolved than simple ``ident(string):value(string)``
  
          Arguments:
              rule (tinycss2.ast.QualifiedRule): Qualified rule object as
                  returned by  tinycss2.
  
          Returns:
              dict: Dictionnary of retrieved variables and properties.
          """
          data = OrderedDict()
  
          current_key = None
  
          for token in rule.content:
              # Assume first identity token is the property name
              if token.type == 'ident':
                  # Ignore starting '-' from css variables
                  name = token.value
                  if name.startswith('-'):
                      name = name[1:]
  
                  current_key = name
                  data[current_key] = None
  
              # Assume first following string token is the property value.
              if token.type == 'string':
                  data[current_key] = token.value
  
          return data