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).

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)