@classdef.method("insert", index="int", other="str")
    @check_frozen()
    def method_insert(self, space, index, other):
        if index < 0:
            index += self.length() + 1
        if not 0 <= index <= self.length():
            raise space.error(space.w_IndexError,
                "index %d out of string" % index
            )
        self.strategy.to_mutable(space, self)
        self.strategy.insert(self.str_storage, index, other)
        return self
dataset/ETHPy150Open topazproject/topaz/topaz/objects/stringobject.py/W_StringObject.method_insert/original