func (b *block) toGNU() *headerGNU     { return (*headerGNU)(b) }
func (b *block) toSTAR() *headerSTAR   { return (*headerSTAR)(b) }
func (b *block) toUSTAR() *headerUSTAR { return (*headerUSTAR)(b) }
func (b *block) toSparse() sparseArray { return sparseArray(b[:]) }

// getFormat checks that the block is a valid tar header based on the checksum.
// It then attempts to guess the specific format based on magic values.

		}

		if s.isExtended()[0] > 0 {
			// There are more entries. Read an extension header and parse its entries.
			if _, err := mustReadFull(tr.r, blk[:]); err != nil {
				return nil, err
			}
			s = blk.toSparse()
			continue
		}
		return spd, nil // Done
	}
}

// readGNUSparseMap1x0 reads the sparse map as stored in GNU's PAX sparse format
// version 1.0. The format of the sparse map consists of a series of

		if format != FormatUnknown {
			blk.setFormat(format)
		}
		out = append(out, blk[:]...)

		// Write extended sparse blocks.
		for len(sps) > 0 {
			var blk block
			sps = populateSparseMap(blk.toSparse(), sps)
			out = append(out, blk[:]...)
		}
		return out
	}

	makeSparseStrings := func(sp []sparseEntry) (out []string) {
		var f formatter
		for _, s := range sp {
			var b [24]byte

      return null;
    }
  }

  @GwtIncompatible // Floats.tryParse
  private static void checkTryParse(String input) {
    assertThat(Floats.tryParse(input)).isEqualTo(referenceTryParse(input));
  }

  @GwtIncompatible // Floats.tryParse
  private static void checkTryParse(float expected, String input) {
    assertThat(Floats.tryParse(input)).isEqualTo(Float.valueOf(expected));
  }

    tryParseAndAssertEquals(LEAST, Integer.toString(LEAST));
    assertThat(Ints.tryParse("")).isNull();
    assertThat(Ints.tryParse("-")).isNull();
    assertThat(Ints.tryParse("+1")).isNull();
    assertThat(Ints.tryParse("9999999999999999")).isNull();
    assertWithMessage("Max integer + 1")
        .that(Ints.tryParse(Long.toString(((long) GREATEST) + 1)))
        .isNull();
    assertWithMessage("Max integer * 10")

    tryParseAndAssertEquals(LEAST, Integer.toString(LEAST));
    assertThat(Ints.tryParse("")).isNull();
    assertThat(Ints.tryParse("-")).isNull();
    assertThat(Ints.tryParse("+1")).isNull();
    assertThat(Ints.tryParse("9999999999999999")).isNull();
    assertWithMessage("Max integer + 1")
        .that(Ints.tryParse(Long.toString(((long) GREATEST) + 1)))
        .isNull();
    assertWithMessage("Max integer * 10")

      return null;
    }
  }

  @GwtIncompatible // Floats.tryParse
  private static void checkTryParse(String input) {
    assertThat(Floats.tryParse(input)).isEqualTo(referenceTryParse(input));
  }

  @GwtIncompatible // Floats.tryParse
  private static void checkTryParse(float expected, String input) {
    assertThat(Floats.tryParse(input)).isEqualTo(Float.valueOf(expected));
  }

    tryParseAndAssertEquals(MIN_VALUE, Long.toString(MIN_VALUE));
    assertThat(Longs.tryParse("")).isNull();
    assertThat(Longs.tryParse("-")).isNull();
    assertThat(Longs.tryParse("+1")).isNull();
    assertThat(Longs.tryParse("999999999999999999999999")).isNull();
    assertWithMessage("Max long + 1")
        .that(Longs.tryParse(BigInteger.valueOf(MAX_VALUE).add(BigInteger.ONE).toString()))
        .isNull();

    tryParseAndAssertEquals(MIN_VALUE, Long.toString(MIN_VALUE));
    assertThat(Longs.tryParse("")).isNull();
    assertThat(Longs.tryParse("-")).isNull();
    assertThat(Longs.tryParse("+1")).isNull();
    assertThat(Longs.tryParse("999999999999999999999999")).isNull();
    assertWithMessage("Max long + 1")
        .that(Longs.tryParse(BigInteger.valueOf(MAX_VALUE).add(BigInteger.ONE).toString()))
        .isNull();

      return Double.valueOf(input);
    } catch (NumberFormatException e) {
      return null;
    }
  }

  @GwtIncompatible // Doubles.tryParse
  private static void checkTryParse(String input) {
    Double expected = referenceTryParse(input);
    assertThat(Doubles.tryParse(input)).isEqualTo(expected);
    if (expected != null && !Doubles.FLOATING_POINT_PATTERN.matcher(input).matches()) {