code: def validate_inputs(*arrays, **kwargs):
      arrays = np.broadcast_arrays(*arrays)
      sort_by = kwargs.pop('sort_by', None)
      if kwargs:
          raise ValueError("unrecognized arguments: {0}".format(kwargs.keys()))
      if arrays[0].ndim != 1:
          raise ValueError("Input arrays should be one-dimensional.")
      if sort_by is not None:
          isort = np.argsort(sort_by)
          if isort.shape != arrays[0].shape:
              raise ValueError("sort shape must equal array shape.")
          arrays = tuple([a[isort] for a in arrays])
      return arrays