def register_vcs(vcs):
 if vcs.is_supported():
  key = vcs.name.lower()
  VCS_REGISTRY[key] = vcs
  VCS_CHOICES.append((key, vcs.name))
 return vcs

def register_vcs ( vcs ) : if vcs . is_supported ( ) : key = vcs . name . lower ( ) VCS_REGISTRY [ key ] = vcs VCS_CHOICES . append ( ( key , vcs . name ) ) return vcs
registers vcs if its supported .