code: def pch_emitter(target, source, env):
      
  
      validate_vars(env)
  
      pch = None
      obj = None
  
      for t in target:
          if SCons.Util.splitext(str(t))[1] == '.pch':
              pch = t
          if SCons.Util.splitext(str(t))[1] == '.obj':
              obj = t
  
      if not obj:
          obj = SCons.Util.splitext(str(pch))[0]+'.obj'
  
      target = [pch, obj] # pch must be first, and obj second for the PCHCOM to work
  
      return (target, source)
docs: Adds the object file target.