anchor.diff:  
   4. Variables from the file that included that file using the
      `subninja` keyword.
  +
  +Future work
  +-----------
  +
  +Some pieces I'd like to add:
  +
  +_inotify_.  I had originally intended to make Ninja be memory-resident
  +and to use `inotify` to keep the build state hot at all times.  But
  +upon writing the code I found it was fast enough to run from scratch
  +each time.  Perhaps a slower computer would still benefit from
  +inotify; the data structures are set up such that using inotify
  +shouldn't be hard.
  +
  +_build estimation and analysis_.  As part of build correctness, Ninja
  +keeps a log of the time spent on each build statement.  This log
  +format could be adjusted to instead store timing information across
  +multiple runs.  From that, the total time necessary to build could be
  +estimated, allowing Ninja to print status like "3 minutes until
  +complete" when building.  Additionally, a tool could output which
  +commands are the slowest or which directories take the most time
  +to build.
  +
  +_many others_.  See the `todo` file included in the distribution.
  
positive.code: where `target` is a known output described by `build.ninja` in the
  current directory.
  
  There is no installation step; the only files of interest to user are
  the resulting binary and this manual.
  
  
  Creating .ninja files
  
negative.code: 
  Ninja file reference
  --------------------
  
  A file is a series of declarations.  A declaration can be one of:
  
  1. A rule declaration, which begins with +rule _rulename_+, and
  