Let’s say you need to iterate over of all the characters of a string object and modify every character in some way. You can do it using the for loop.

>>> s1 = 'Dan Dumitrache'
>>> for i in s1:
... print(i, ' ; ')
...
D ;
a ;
n ;
;
D ;
u ;
m ;
i ;
t ;
r ;
a ;
c ;
h ;
e ;

Here, the iterator pulls each element from the list.

>>> s1 = 'DAN'
>>> for i in s1:
... print(s1.lower())
...
dan
dan
dan

Here, the word dan is printed three times because we used the for loop. If you wanted to be printed only once in lowercase letters then just use the print part without the for loop.

Here you have another example:

>>> s1 = 'dan'
>>> for i in range(3):
... print(s1[i].upper())
...
D
A
N

However, if you wanted printed on the same line then you can use end = '' as shown below:

>>> s1 = 'dan'
>>> for i in range(3):
... print(s1[i].upper(), end='')
...
DAN