what is @ used for in python code example

Example 1: what is repr function in python

#The repr() function returns a printable representation of the given object.
Upvote = "Do make an upvote click on the top right corner button."
>>> print(Upvote)
>>> 'Do make an upvote click on the top right corner button.'

>>> print(repr(Upvote))
>>>"'Do make an upvote click on the top right corner button.'"

Example 2: what is join use for in python

>>> sentence = ['this','is','a','sentence']
>>> '-'.join(sentence)
'this-is-a-sentence'