code: def morse_encode(letter):
      pred = next(
          G.predecessors(letter)
      )  # Each letter has only 1 predecessor
      symbol = G[pred][letter]["char"]
      if pred != "":
          return (
              morse_encode(pred) + symbol
          )  # Traversing the trie in reverse
      return symbol
  
label_desc: Use image node_id 1 for calling a global function with example usage: morse_encode(letter) and returns: symbol, unknown