import re
s = "A1:C1000"
r = r"([A-Z]+)(\d+)\b"
def mySub(m):
letter = m.group(1)
contents = m.group(2)
if contents == '1':
return letter + '10'
if contents == '1000':
return letter + '999'
print re.sub(r, mySub, s)
aW1wb3J0IHJlCgpzID0gIkExOkMxMDAwIgpyID0gciIoW0EtWl0rKShcZCspXGIiCgpkZWYgbXlTdWIobSk6CglsZXR0ZXIgPSBtLmdyb3VwKDEpCgljb250ZW50cyA9IG0uZ3JvdXAoMikKCWlmIGNvbnRlbnRzID09ICcxJzoKCQlyZXR1cm4gbGV0dGVyICsgJzEwJwoJaWYgY29udGVudHMgPT0gJzEwMDAnOgoJCXJldHVybiBsZXR0ZXIgKyAnOTk5JwoKcHJpbnQgcmUuc3ViKHIsIG15U3ViLCBzKQ==