code: def _loadDescriptionFile(descriptionPyPath):
    
    global g_descriptionImportCount
  
    if not os.path.isfile(descriptionPyPath):
      raise RuntimeError(("Experiment description file %s does not exist or " + \
                          "is not a file") % (descriptionPyPath,))
  
    mod = imp.load_source("pf_description%d" % g_descriptionImportCount,
                          descriptionPyPath)
    g_descriptionImportCount += 1
  
    if not hasattr(mod, "descriptionInterface"):
      raise RuntimeError("Experiment description file %s does not define %s" % \
                         (descriptionPyPath, "descriptionInterface"))
  
    if not isinstance(mod.descriptionInterface, exp_description_api.DescriptionIface):
      raise RuntimeError(("Experiment description file %s defines %s but it " + \
                          "is not DescriptionIface-based") % \
                              (descriptionPyPath, name))
  
    return mod
docs: Loads a description file and returns it as a module.
  
    descriptionPyPath: path of description.py file to load