Python - Why result is adbdc and NOT adbdcd?

Question

l = ['a','b','c']
print('d'.join(l))

Answer 1

concatenates the elements with 'd' (or puting 'd' between them) or joins elements of l with char 'd'.
If it was adbdcd then it should be one more 'd' before a, thus 'd'adbdc'd'.
It is how it works... I mean thats it.
Also join is used for returning lists as strings.

check also (join is already explained):
https://www.sololearn.com/Discuss/1744468/how-to-use-join-work-JUMP_LINK__&&__python__&&__JUMP_LINK

Now, why it is constructed like that? This is a hard question. It's just the language architecture... At the creation time, someone thought that such a method could be usefull and he just implemented it.

Answer 2

Because method join returns a string made from the elements of an iterable.
The separator between elements is the string providing this method.

'-'.join(['A', 'B', 'C']) # '-' string is the seprator 'A-B-C'