@Udf
  public int instr(final String str, final String substring) {
    return instr(str, substring, 1);
  }
@Test
  public void shouldExtractFromStartForPositivePositions() {
    assertThat(udf.instr("CORPORATE FLOOR", "OR"), is(2));
    assertThat(udf.instr("CORPORATE FLOOR", "OR", 3), is(5));
    assertThat(udf.instr("CORPORATE FLOOR", "OR", 3, 2), is(14));
    assertThat(udf.instr("CORPORATE FLOOR", "OR", 3, 5), is(0));

    assertThat(udf.instr("CORPORATE FLOOR", "ATE"), is(7));
    assertThat(udf.instr("CORPORATE FLOOR", "ATE", 2), is(7));
    assertThat(udf.instr("CORPORATE FLOOR", "ATE", 3, 2), is(0));
  }