@jit.unroll_safe
    def find_env_in_chain_speculate(self, target, env_structure, env):
        jit.promote(self)
        jit.promote(env_structure)
        while env_structure is not None:
            if env_structure is self:
                if env is target:
                    return env
            env = env.get_prev(env_structure)
            env_structure = env_structure.prev
        return target
find env 'target' of shape 'self' in environment chain 'env', described
dataset/ETHPy150Open samth/pycket/pycket/env.py/SymList.find_env_in_chain_speculate