How do I capitalize only the alphabets not the alphanumerics

def solve(s):
    if s.isalnum():
        Empty= s.split()
        Empty2= ""
        for string in Empty:
            if isinstance(string, str):
                if any(char.isdigit() for char in string):
                    Empty2 += string.lower()
                    Empty2 += " "
                else:
                    Empty2+= string.capitalize()
                    Empty2+= " "
        return Empty2
    else:
        return s.title()

if any(char.isdigit() for char in string):
    Empty2 += string.lower()
    Empty2 += " "