Convert an excel or spreadsheet column letter to its number in Pythonic fashion

Question

Is there a more pythonic way of converting excel-style columns to numbers (starting with 1)?

Working code up to two letters:

Answer 1

For index that starts from zero (e.g. A = 0, B = 1, and so on):

def col_to_index(col):
    A = ord('A')
    return sum(i * 26 + (ord(c) - A) for i, c in enumerate(col[::-1].upper()))