code: def listcodecs(dir):
      names = []
      for filename in os.listdir(dir):
          if filename[-3:] != ".py":
              continue
          name = filename[:-3]
          # Check whether we've found a true codec
          try:
              codecs.lookup(name)
          except LookupError:
              # Codec not found
              continue
          except Exception as reason:
              # Probably an error from importing the codec; still it's
              # a valid code name
              if _debug:
                  print(
                      "* problem importing codec %r: %s"
                      % (name, reason)
                  )
          names.append(name)
      return names
  
label_desc: Use image node_id 1 for calling a global function with example usage: listcodecs(dir) and returns: names