# -*- coding: UTF-8 -*-
def split_string_with_step(my_string, step):
    """
    create list of strings by split a big one with step
    """
    if (
        not isinstance(my_string, str) or
        not isinstance(step, int)
    ):
        raise NotImplementedError
    pos = 0
    my_list = []
    for char in range((len(my_string)//step)+1):
        my_list.append(my_string[pos:pos+step])
        pos+=step
    if len(''.join(my_list)) == len(my_string):
        return my_list
    else:
        raise NotImplementedError

# ~# example :

my_string_test = """MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA5qeHbZZQFLnXoiBrQb8udZxmz3FGnFFd63/qrlQ4GBpbf62DVMVEgZJOJFGEKW09KvgikBHtpRitYvW4g54s2/RVSK+6qpPq+Iw3jHuUrO3rkDW/2J5pcczUaxRQHuRyL9/fm7m9m4JMnFyTXV8Bn7hWrfH2VkVRz2wKd8BzBmMX1alCaVLLTz8NP2ccBO3U9Zyt4ZXPki5SOV3I421F9324y2VVtuqUewAGeYhGjcQ51yKlBggrkp+E1p9dmola7Xw6/UG3DIrgv88NeqAYiYjAfzMRwOjbQA2mhi770kINJKOWL59FbGcFxTcakzfdTljPHxWJy+u5aAoZNZQIDAQAB"""
my_list_of_string = split_string_with_step(my_string_test, 6)

for x in my_list_of_string:
print(x)

"""
résultats :
MIIBIj
ANBgkq
hkiG9w
0BAQEF
AAOCAQ
8AMIIB
CgKCAQ
EA5qeH
bZZQFL
nXoiBr
Qb8udZ
xmz3FG
nFFd63
/qrlQ4
GBpbf6
2DVMVE
gZJOJF
GEKW09
KvgikB
HtpRit
YvW4g5
4s2/RV
SK+6qp
Pq+Iw3
jHuUrO
3rkDW/
2J5pcc
zUaxRQ
HuRyL9
/fm7m9
m4JMnF
yTXV8B
n7hWrf
H2VkVR
z2wKd8
BzBmMX
1alCaV
LLTz8N
P2ccBO
3U9Zyt
4ZXPki
5SOV3I
421F93
24y2VV
tuqUew
AGeYhG
jcQ51y
KlBggr
kp+E1p
9dmola
7Xw6/U
G3DIrg
v88Neq
AYiYjA
fzMRwO
jbQA2m
hi770k
INJKOW
L59FbG
cFxTca
kzfdTl
jPHxWJ
y+u5aA
oZNZQI
DAQAB
"""