@Test
public void testCanSign() throws Exception {

    KeyPair keypair;
    keypair = KeyPair.fromSecretSeed("SDJHRQF4GCMIIKAAAQ6IHY42X73FQFLHUULAPSKKD4DFDM7UXWWCRHBE");
    assertTrue(keypair.canSign());
    keypair = KeyPair.fromAccountId("GABXJTV7ELEB2TQZKJYEGXBUIG6QODJULKJDI65KZMIZZG2EACJU5EA7");
    assertFalse(keypair.canSign());
}