if (r instanceof Reader) {
      copyReaderToBuilder((Reader) r, sb);
    } else {
      copy(r, sb);
    }
    return sb;
  }

  /**
   * Reads all of the lines from a {@link Readable} object. The lines do not include
   * line-termination characters, but do include other leading and trailing whitespace.
   *
   * <p>Does not close the {@code Readable}. If reading files or resources you should use the {@link

  }

  /**
   * Streams lines from a {@link File}, stopping when our callback returns false, or we have read
   * all of the lines.
   *
   * @param file the file to read from
   * @param charset the charset used to decode the input stream; see {@link StandardCharsets} for
   *     helpful predefined constants
   * @param callback the {@link LineProcessor} to use to handle the lines
   * @return the output of processing the lines

    }

    private static char[] nines() {
      char[] nines = new char[ZEROES.length()];
      for (int i = 0; i < ZEROES.length(); i++) {
        nines[i] = (char) (ZEROES.charAt(i) + 9);
      }
      return nines;
    }

    static final CharMatcher INSTANCE = new Digit();

    private Digit() {
      super("CharMatcher.digit()", zeroes(), nines());
    }
  }

  }

  /**
   * Returns a splitter that considers any subsequence matching {@code pattern} to be a separator.
   * For example, {@code Splitter.on(Pattern.compile("\r?\n")).split(entireFile)} splits a string
   * into lines whether it uses DOS-style or UNIX-style line terminators.
   *
   * @param separatorPattern the pattern that determines whether a subsequence is a separator. This
   *     pattern may not match the empty string.

     * --- System.out.println(input + " " + simplifyPath(input));
     * --- fail(). (If the test were to pass, its output would be hidden.)
     * - Run the test.
     * - Pull the relevant lines of output from the test into a testcases file.
     * - Test the output:
     * --- cat testcases | while read L; do
     *       X=($L)
     *       A=$( cd /b/c && sudo mkdir -p ${X[0]} && cd ${X[0]} && pwd |

     * --- System.out.println(input + " " + simplifyPath(input));
     * --- fail(). (If the test were to pass, its output would be hidden.)
     * - Run the test.
     * - Pull the relevant lines of output from the test into a testcases file.
     * - Test the output:
     * --- cat testcases | while read L; do
     *       X=($L)
     *       A=$( cd /b/c && sudo mkdir -p ${X[0]} && cd ${X[0]} && pwd |

    }
    reader.close();
    writer.close();

    assertExpectedString(writer.toString());
  }

  public void testLines() throws IOException {
    try (Stream<String> lines = source.lines()) {
      assertExpectedLines(lines.collect(toImmutableList()));
    }
  }

  public void testCopyTo_appendable() throws IOException {
    StringBuilder builder = new StringBuilder();

   */
  @CanIgnoreReturnValue // some uses know that their processor never returns false
  boolean processLine(String line) throws IOException;

  /** Return the result of processing all the lines. */
  @ParametricNullness
  T getResult();

  }

  /**
   * Returns a splitter that considers any subsequence matching {@code pattern} to be a separator.
   * For example, {@code Splitter.on(Pattern.compile("\r?\n")).split(entireFile)} splits a string
   * into lines whether it uses DOS-style or UNIX-style line terminators.
   *
   * @param separatorPattern the pattern that determines whether a subsequence is a separator. This
   *     pattern may not match the empty string.

   * scattered in memory and thus don't interfere much with each
   * other. But Atomic objects residing in arrays will tend to be
   * placed adjacent to each other, and so will most often share
   * cache lines (with a huge negative performance impact) without
   * this precaution.
   *
   * In part because Cells are relatively large, we avoid creating
   * them until they are needed.  When there is no contention, all