Write a function 
`titleToNumber(title) or title_to_number(title) or titleToNb title ...`
(depending on the language)
that given a column title as it appears in an Excel sheet, returns its corresponding column number. All column titles will be uppercase.
Examples:
```
titleTonumber('A') === 1
titleTonumber('Z') === 26
titleTonumber('AA') === 27
```
from string import ascii_uppercase
def title_to_number(t):
  return 0 if len(t) == 0 else (ascii_uppercase.index(t[0]) + 1) * 26 ** (len(t) - 1) + title_to_number(t[1:])
from string import ascii_uppercase
def title_to_number(t):
  return 0 if len(t) == 0 else (ascii_uppercase.index(t[0]) + 1) * 26 ** (len(t) - 1) + title_to_number(t[1:])