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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fix_e731(self, result):
 """Fix do not assign a lambda expression check."""

        (line_index, _, target) = get_index_offset_contents(result,
                                                            self.source)
        match = LAMBDA_REGEX.search(target)
        if match:
            end = match.end()
            self.source[line_index] = '{}def {}({}): return {}'.format(
                target[:match.start(0)], match.group(1), match.group(2),
                target[end:].lstrip())