Python：第一个不匹配字符的索引？

Question

Python 2.7: I'm wondering if there's an inverted version of the index operation for a list. I can't use index because the value that will not match is unknown.

Here's an example:

myString = "aaaaaxcbaa"
pos = myString.not_index('a')
# pos should be 5
myString = "bbzcbaa"
pos = myString.not_index('b')
# pos should be 2
myString = "xxxxx"
pos = myString.not_index('x')
# this can throw an error similar to "index"

Does such a thing exist?

Right now I'm simply iterating the list item-by-item but it feels like this should be a bit simpler.

Answer 1

No.

>>> next(i for (i, e) in enumerate("aaaaaxcbaa") if e != "a")
5