There 's an invalid syntax error but i don't know what's wrong with it.

[kakarot vegeta]

There 's an invalid syntax error but i don't know what's wrong with it.
the error says

Invalid syntax: print variation_strin g

import itertools

variations = itertools.product('ab', repeat=4)
for variations in variations:
        variation_string = ""
        for letter in variations:
                variation_string += letter
        print variation_string

[Mariostg]

Read your line 5 again. How about
For variation in variations
Then change line 7 accordingly.

[dwblas]

What version of Python are you using? If it is 3.x, then print is a function:
print(variation _string)

for variations in variations:

While this is a terrible coding style, it will run as each "variations " points to a different memory address, because for() loop variables are local to the loop (but I wouldn't want to modify or debug it).

[Dev Player]

Cut and past the code below and save in a different file; although I see you code in my webbrowser I see that code in the fonts on my system; It's possible the fonts on your system are hiding your syntax error. Although I doubt that.

Your code works fine on my pc. WinXP Pro-32bit SP3, Python 2.7

import itertools
print('"""')
variations = itertools.product('ab', repeat=4)
for variation in variations:
    # print( variation )
    variation_string = ""
    
    for letter in variation:
        variation_string += letter
        # print(variation_string)
    print(variation_string)
print('"""')

"""
aaaa
aaab
aaba
aabb
abaa
abab
abba
abbb
baaa
baab
baba
babb
bbaa
bbab
bbba
bbbb
"""