How to use the fastecdsa.curve.P256 function in fastecdsa

def new_keypair(self):
        """ 生成公私钥的键值对"""
        priv_key = keys.gen_private_key(curve.P256)

        pub_key = keys.get_public_key(priv_key, curve.P256)

        pub_key = "".join([str(pub_key.x), str(pub_key.y)])

        self.private_key = priv_key
        self.pub_key = pub_key
        return priv_key, pub_key

def new_keypair(self):
        """ 生成公私钥的键值对"""
        priv_key = keys.gen_private_key(curve.P256)

        pub_key = keys.get_public_key(priv_key, curve.P256)

        pub_key = "".join([str(pub_key.x), str(pub_key.y)])

        self.private_key = priv_key
        self.pub_key = pub_key
        return priv_key, pub_key

def infer_local_type(curve: str) -> curve_types.Curve:
    """converts a ``str`` representation of some elliptic curve to a
    representation understood by the backend of this module."""
    if curve == "P-256":
        return curve_types.P256
    else:
        raise NotImplementedError()

def get_new_priv_key() -> str:
    '''
    Returns a random private key in hex format
    '''
    return '{:x}'.format(keys.gen_private_key(curve.P256))