code: def get_ed25519ll():
      
      global ed25519ll
  
      if not ed25519ll:
          try:
              import ed25519ll  # fast (thousands / s)
          except (ImportError, OSError):  # pragma nocover
              from . import ed25519py as ed25519ll  # pure Python (hundreds / s)
          test()
  
      return ed25519ll
docs: Lazy import-and-test of ed25519 module