# [Japt](https://github.com/ETHproductions/japt), 4 bytes

    rP'!

[Try it](https://petershaggynoble.github.io/Japt-Interpreter/?v=1.4.6&code=clAnIQ&input=IjEgMiAzIDQgNSA2CjEyOTU5MSAxMjkwMTIgMTI5MTI3IDEyOTU4MgoKMCI)

    r      Replace
     P     all empty strings "" with
      '!   An exclamation mark (If '!' wasn't a special character in Japt I could remove the quote)