docs: def lookup_path(bin_name):
      """Calls to external binaries can't depend on $PATH
      """
      paths = ('/usr/local/sbin/', '/usr/local/bin/', '/usr/sbin/', '/usr/bin/')
      for p in paths:
          fq_path = p + bin_name
          found = os.path.isfile(fq_path) and os.access(fq_path, os.X_OK)
          if found:
              return fq_path
      return False