code: def _resolve_attribute(self, attribute):
          
          value = self.attributes[attribute]
          if not value:
              return None
          resolved_value = re.sub('\$\((.*?)\)',self._resolve_attribute_match, value)
          return resolved_value
docs: Recursively replaces references to other attributes with their value.
  
          Args:
              attribute (str): The name of the attribute to resolve.
  
          Returns:
              str: The resolved value of 'attribute'.