def get_valid_os_versions():
 os_versions = []
 try:
  for breed in get_valid_breeds():
   os_versions += SIGNATURE_CACHE['breeds'][breed].keys()
 except:
  pass
 return uniquify(os_versions)

def get_valid_os_versions ( ) : os_versions = [ ] try : for breed in get_valid_breeds ( ) : os_versions += SIGNATURE_CACHE [ 'breeds' ] [ breed ] . keys ( ) except : pass return uniquify ( os_versions )
return a list of valid os-versions found in the import signatures .