import string

s = 'BIG BANG'
r = ' ' + string.ascii_uppercase
d = {j: i for i, j in enumerate(r)}
t = 0
for i in s:
  t += d[i]

print(t)

"""
>>> import string
>>>
>>> s = 'BIG BANG'
>>> r = ' ' + string.ascii_uppercase
>>> d = {j: i for i, j in enumerate(r)}
>>> t = 0
>>> for i in s:
...   t += d[i]
...
>>> print(t)
42
"""