I'm not sure what I'm doing wrong. Can someone please give me a hint?

// Enter your code below
extension String { 

  func transform(_ argc: (String) -> String ) -> String { 
    return argc(self)
  }

  func removeVowels(from string: String) -> String {
    var newString = ""
    for char in string.characters {
      if !(char == "a" || char == "A" || char == "e" || char == "E" || char == "i" || char == "I" || char == "o" || char == "O" || char == "u" || char == "U" ){
        newString = newString + char
      }
    }
    return newString
  }

}