
    Design a function that generates a single-character checksum from a transaction security token string by summing the ASCII values of all characters in the token and performing modulo 26 operation, where the resulting character serves as a quick verification marker in the bank's fraud detection system. The function must process any length of transaction token string and return a single alphabetic character (A-Z) that can be used for rapid pattern matching across different banking channels.
    

    
def get_Char(strr):
    """
    Design a function that generates a single-character checksum from a transaction security token string by summing the ASCII values of all characters in the token and performing modulo 26 operation, where the resulting character serves as a quick verification marker in the bank's fraud detection system. The function must process any length of transaction token string and return a single alphabetic character (A-Z) that can be used for rapid pattern matching across different banking channels.
    

    """
def get_Char(strr):
    """
    Design a function that generates a single-character checksum from a transaction security token string by summing the ASCII values of all characters in the token and performing modulo 26 operation, where the resulting character serves as a quick verification marker in the bank's fraud detection system. The function must process any length of transaction token string and return a single alphabetic character (A-Z) that can be used for rapid pattern matching across different banking channels.
    

    """
    summ = 0
    for i in range(len(strr)):
        summ += ord(strr[i]) - ord('a') + 1
    if summ % 26 == 0:
        return ord('z')
    else:
        summ = summ % 26
        return chr(ord('a') + summ - 1)