Does the given private key info represent
    a single signature bundle? (i.e. one private key)?

    i.e. is this key a private key string?

def btc_is_singlesig(privkey_info, **blockchain_opts):
    """
    Does the given private key info represent
    a single signature bundle? (i.e. one private key)?

    i.e. is this key a private key string?
    """
    try:
        jsonschema.validate(privkey_info, PRIVKEY_SINGLESIG_SCHEMA)
        return True
    except ValidationError as e:
        return False