anchor.diff:  that do this whenever possible. This design gives a nice speedup to incremental
   builds where most of the time is spent signing and checking file metadata.
   
  -==== Reliably support code generation ====
  +==== Reliably support code generation
   
   Tundra is designed around the concept of build passes, which segment the input
   dependency graph into serialized regions. Dependencies (even implicit
  
positive.code: 
  Stay away from funny characters in the names, alphanumeric is a safe bet.
  
  ==== Native Unit Config property ====
  
  Specifies what configuration(s) this unit will be present in. Configuration
  pattern matching is applied as usual. For example, to include a unit only in
  
negative.code: but it will still be present so there's no need to remove it from depenency
  lists.
  
  ==== Native Unit Propagate property
  
  A nested block of settings to be propagated onto units that depend on this
  unit. This is mostly useful for the `ExternalLibrary` unit type which serves as
  