str.join()?

[buran]

With str.join() you call instance method directly on the class. It expects to implicitly receive instance of the class - that will be used as separator and an iterable, whose elements will be concatenated with the use of the separator

that's why @Griboulis example

str.join('a', 'bc') # 'a' is the instance of str and 'bc' is the iterable

is identical with

'a'.join('bc')

and yield the same output.