docs: def fromkeys(cls, keys, value=None, names=None):
          '''
          Create a new dictionary with keys from ``keys`` and values set to ``value``.
  
          fromkeys() is a class method that returns a new dictionary. ``value`` defaults to None.
  
          Length of ``keys`` must not exceed one because no duplicate values are allowed.
  
          Optional ``names`` can be provided for index names (of length 2).
          '''
          N = len(keys)
          if N > 1:
              raise ValueError('Length of keys (%s) must not exceed one because '
                               'no duplicate values are allowed' % (N,))
          items = [[keys[0], value]] if N == 1 else []
          return cls(items, names)