@Test
public void splitThenTrim_intoTwoParts_canSplit() {

  assertThat(first('=').splitThenTrim(" foo =bar", (String k, String v) -> k)).isEqualTo("foo");
  assertThat(first('=').splitThenTrim("foo = bar ", (String k, String v) -> v)).isEqualTo("bar");
}