Find Longest Awesome Substring LeetCode solution in Python

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class Solution:
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    def longestAwesome(self, s: str) -> int:
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        # li = [1, 2, 4, 8, 16, 32, 64, 128, 256, 512]
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        li = [2**i for i in range(10)]
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        # checker = {0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512}
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        checker = set(li)
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        checker.add(0)
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        # di: k = prefix xor, v = the first idx I got a new prefix_xor_value.
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        di = collections.OrderedDict({0: -1})
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        maxLength = prefix_xor = 0
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        for i in range(len(s)):
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            prefix_xor ^= li[int(s[i])]
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            # Found a new prefix_xor_value
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            if prefix_xor not in di:
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                di[prefix_xor] = i
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            # XOR operation with previous prefix_xor_value
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            for key in di.keys():
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                if i - di[key] <= maxLength:
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                    break
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                # s[di[key] : i] is Awesome Substring
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                if key ^ prefix_xor in checker:
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                    maxLength = i - di[key]
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        return maxLength