Функция выращивания JavaScript

decodeMorse = function(morseCode){
  function decodeMorseLetter(letter) {
    return MORSE_CODE[letter];
  }
  function decodeMorseWord(word) {
    return word.split(' ').map(decodeMorseLetter).join('');
  }
  return morseCode.trim().split('   ').map(decodeMorseWord).join(' ');
}
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