from functools import reduce


def excel_col_letter_to_index(x): 
    """
    Convert a 'AH','C', etc. style Excel column reference to its integer
    equivalent.

    @param x (str) The letter style Excel column reference.

    @return (int) The integer version of the column reference.
    """
    return reduce(lambda s,a:s*26+ord(a)-ord('A')+1, x, 0)