code: def from_regular_arrays(self, arrays):
          
          return self._mytype(join_struct_arrays([
              array.astype(dtype)
              for dtype, array in zip(self._dtypes, arrays)
          ]))
docs: Merges a list of arrays (of the same shape) of dtypes 
          corresponding to the factor domains into a single array 
          with the dtype of the ``ProductDomain``.
  
          :param list array: A list with each element of type ``np.ndarray``
  
          :rtype: `np.ndarray`