code: def get_os_file_names(files):
          
  
          fnames = []
          for f in files:
              if utils.is_str(f):
                  fnames.append(f)
              elif isinstance(f, file_configuration_t):
                  if f.content_type in (
                          file_configuration_t.CONTENT_TYPE.STANDARD_SOURCE_FILE,
                          file_configuration_t.CONTENT_TYPE.CACHED_SOURCE_FILE):
  
                      fnames.append(f.data)
              else:
                  pass
          return fnames
docs: returns file names
  
          :param files: list of strings and\\or :class:`file_configuration_t`
                        instances.
          :type files: list