This script mimics part of the functionality of tpope/vim-surround.
Map it as follows.
nnoremap yss :csx SimpleSurround<CR>
Open the text file and enter the following.
Hello !!
In normal mode, enter as follows.
yss
Then enter the following:
t
Then the following is displayed in the command margin.
<
Continue typing as follows, then press the Enter key.
p
The text file will look like the following.
<p>Hello !!</p>