anchor.diff:  ninja input files.  Ninja by itself is unlikely to be useful for most
   projects.
   
  -Here are some of the features Ninja adds to make.  (These sorts of
  +Here are some of the features Ninja adds to Make.  (These sorts of
   features can often be implemented using more complicated Makefiles,
   but they are not part of make itself.)
   
  
positive.code: 
  ----
  rule demo
    command = echo "this is a demo of $foo'
  
  build out: demo
    foo = bar
  
negative.code: http://neugierig.org/software/chromium/notes/2011/02/ninja.html[my
  work on the Chromium browser project], which has over 30,000 source
  files and whose other build systems (including one built from custom
  non-recursive Makefiles) would take ten seconds to start building
  after changing one file.  Ninja is under a second.
  
  Philosophical overview
  ~~~~~~~~~~~~~~~~~~~~~~
  