Even if i put it in exactly the way you did:
>>> import re
>>> charmatcher = re.compile(r' [A-Z] [\d]?')
>>>
>>> ext = dict(D="V1", O="M1", G="S1")
>>> std = dict(S="H")
>>>
>>> decode_replacements ={}
>>> decode_replacements.update([(std[key], key) for key in std])
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: keys