Python - Caeser Cipher Not Giving Right Output

[Yozuru]

Hello good people, I am able to run my code and it works fine.

However I did a test of:

two('y', 'z')

and received a '\x92' output instead of a 'x' output.

This is my code so far:

def chartonum(ch):
    return ord(ch) - 97 

def numtochar(n):
    return chr(n + 97) 

def two(c1 , c2):
    c1 = chartonum(c1)
    c2 = chartonum(c2)
    return numtochar(c1 + c2 %26)

I am thinking I have messed up on my mod 26, however, I am at a lost where I might have went wrong in that. Any help would be appreciated.

EDIT: SOLVED.

Line 10 error in precedence. so ((c1 + c1)%26)

[Yozuru]

I have found my answer, it was in a problem in line 10 with precedence. Such a simple error that have cost me a few hours. Hope this is useful to those who will see this.