How to iterate between each character, any help appreciated thanks!

[slender parcel]

Hey everyone, I'm just doing string operations and indexing and here is a very short piece of code, in this example I am trying to add '--' between each character from my input but It never works and the output is wrong, I've tried many times with different variations of [:1] and [0:] etc but I never can add anything between the characters, any help would be much appreciated,

[rough rover]

+you can use delimiter.join(text) with delimiter being '--' and text being useri

[slender parcel]

Oh my godness it worked, thank you so much :DDD