def common_prefix(s1, s2):
        """
        Return the common prefix of two lines.
        """
        index = min(len(s1), len(s2))
        while s1[:index] != s2[:index]:
            index -= 1
        return s1[:index]

        Return the common prefix of two lines.
        
product/runtime/src/main/python/pkg_resources/_vendor/jaraco/text/__init__.py