anchor.diff:  
   [source,yaml]
   ----
  -collectors:
  -- collector_type: COMMAND
  -  args:
  +sources:
  +- type: COMMAND
  +  attributes:
       args: [-qa]
       cmd: /bin/rpm
   ----
   [source,yaml]
   ----
  -collectors:
  -- collector_type: FILE
  -  args:
  +sources:
  +- type: FILE
  +  attributes:
       path_list:
         - /root/.bashrc
         - /root/.cshrc
  
positive.code: 
  == Conditions
  
  Artifact conditions are implemented using the
  link:https://code.google.com/p/objectfilter/[objectfilter] system that allows
  you to apply complex conditions to the attributes of an object. Artifacts can
  apply conditions to any of the Knowledge Base object attributes as defined in
  the GRR link:https://code.google.com/p/grr/source/browse/proto/knowledge_base.proto[knowledge_base.proto].
  TODO: move this out of GRR into something local.
  
  Since OS conditions are a very common constraint, this has been provided as a
  separate option "supported_os" to simplify syntax.  Under the hood, this:
  
negative.code: conditions: [os_major_version >= 6 and time_zone == 'America/Los_Angeles']
  ----
  
  == Minimize the Number of Definitions by Using Multiple Sources
  
  To minimize the number of artifacts in the list, combine them using the
  supported_os and conditions attributes where it makes sense. e.g. rather than
  