Need clarification on how the str.join() method works

Question

I wrote this code in python:

def master_yoda(text):
    a=text.split()
    a=a[::-1]
    a=" ".join(a)
    return a

Which gives the output 'home am I' executed with master_yoda('I am home').

Whereas if I put an empty space in between — a=''.join()a — the output becomes 'homeamI'. Why does it happen?

Answer 1

The string that invokes the join method is used to join the elements, i.e., it appears between each element of the list in the result.

>>> "-".join(["a", "b", "c"])
'a-b-c'
>>> "1".join(["a", "b", "c"])
'a1b1c'
>>> "hi".join(["a", "b", "c"])
'ahibhic'

The empty string is also a string; it just has 0 characters in it. Therefore, in the result, there are zero characters between each element of the list.

>>> "".join(["a", "b", "c"])
'abc'