code: public static Matcher<Long> closeTo(Long operand, Long error) {
          return new LongCloseTo(operand, error);
      }
docs: Creates a matcher of {@link Long}s that matches when an examined Long is equal
  to the specified <code>operand</code>, within a range of +/- <code>error</code>. The comparison for equality
  is done by BigDecimals {@link Long#compareTo(Long)} method.
  
  For example:
  <pre>assertThat(103L, is(closeTo(100, 0.03)))</pre>
  
  @param operand the expected value of matching Long
  @param error   the delta (+/-) within which matches will be allowed
  @return the matcher