code: def parse_secured_key(secured_key,
          key_nonce_separator='.',
          nonce_length=4,
          base=BASE62):
      
      parts = secured_key.split(key_nonce_separator)
      if len(parts) != 2:
          raise ValueError('Invalid secured key format')
  
      (key, nonce) = parts
      if len(nonce) != nonce_length:
          raise ValueError('Invalid length of the key nonce')
  
      return key_to_int(key, base=base), key, nonce
docs: Parse a given secured key and return its associated integer, the key
      itself, and the embedded nonce.
  
      @param secured_key a string representation of a secured key composed
             of a key in Base62, a separator character, and a nonce.
  
      @param key_nonce_separator: the character that is used to separate the
             key and the nonce to form the secured key.
  
      @param nonce_length: the number of characters to compose the nonce.
  
      @param base: a sequence of characters that is used to encode the
             integer value.
  
      @return: a tuple ``(value, key, nonce)``:
               * ``value``: the integer value of the key.
               * ``key``: the plain-text key.
               * ``nonce``: "number used once", a pseudo-random number to
                 ensure that the key cannot be reused in replay attacks.
  
      @raise ValueError: if the format of the secured key is invalid, or if
             the embedded nonce is of the wrong length.