code: public @NotNull DoubleAssert isLessThan(double other) {
      if (compareTo(other) < 0) {
        return this;
      }
      failIfCustomMessageIsSet();
      throw failure(unexpectedGreaterThanOrEqualTo(actual, other));
    }
docs: Verifies that the actual {@code Double} is less than the given one.
  
  @param other the given value.
  @return this assertion object.
  @throws AssertionError if the actual {@code Double} is not less than the given one.