code: def get_fullpath(self, fullname=None, relative_to=None):
          
          # if is an empty path
          if not fullname:
              return fullname
  
          isabs = os.path.isabs(fullname)
  
          path, name = os.path.split(fullname)
  
          if not name:  # path to a folder
              return None
          else:  # path to a file
              if isabs:
                  return fullname
              else:
                  return os.path.join(self.case_path, path, name)
docs: Return the original full path if full path is specified, otherwise
          search in the case file path