How to use the pymongocrypt.binding.ffi function in pymongocrypt

def __init__(self, options):
        """Abstracts libmongocrypt's mongocrypt_t type.

        :Parameters:
          - `options`: A :class:`MongoCryptOptions`.
        """
        self.__opts = options
        self.__crypt = None

        if not isinstance(options, MongoCryptOptions):
            raise TypeError("options must be a MongoCryptOptions")

        self.__crypt = lib.mongocrypt_new()
        if self.__crypt == ffi.NULL:
            raise MongoCryptError("unable to create new mongocrypt object")

        try:
            self.__init()
        except Exception:
            # Destroy the mongocrypt object on error.
            self.close()
            raise

def endpoint(self):
        """The kms hostname to connect over TLS."""
        p = ffi.new("char *[]", 1)
        try:
            if not lib.mongocrypt_kms_ctx_endpoint(self.__ctx, p):
                self.__raise_from_status()
            return _to_string(p[0])
        finally:
            ffi.release(p)

def endpoint(self):
        """The kms hostname to connect over TLS."""
        p = ffi.new("char *[]", 1)
        try:
            if not lib.mongocrypt_kms_ctx_endpoint(self.__ctx, p):
                self.__raise_from_status()
            return _to_string(p[0])
        finally:
            ffi.release(p)

def _create_context(self):
        """Returns a new mongocrypt_ctx_t"""
        ctx = lib.mongocrypt_ctx_new(self.__crypt)
        if ctx == ffi.NULL:
            self.__raise_from_status()
        return ctx