NormalizedString.clear() broken?

[lkurlandski]

Hello. I think there are some problems with NormalizedString (tokenizers 0.15.2).

In the following example, append() works as expected.

from tokenizers import NormalizedString

s = NormalizedString("Hi.")  # NormalizedString(original="Hi.", normalized="Hi.")
s.append("Hello.") # NormalizedString(original="Hi.", normalized="Hi. Hello.")

After using clear(), append() no longer modifies the normalized attribute.

from tokenizers import NormalizedString

s = NormalizedString("Hi.")  # NormalizedString(original="Hi.", normalized="Hi.")
s.clear()  # NormalizedString(original="Hi.", normalized="")
s.append("Hello.")  # NormalizedString(original="Hi.", normalized="")

This is also a problem with prepend.

[ArthurZucker]

Indeed, would you like to have a go at it and open a PR ? 🤗