code: def broadcast_indices(x, minv, ndim, axis):
      
      ret = []
      for dim in range(ndim):
          if dim == axis:
              ret.append(minv)
          else:
              broadcast_slice = [np.newaxis] * ndim
              broadcast_slice[dim] = slice(None)
              dim_inds = np.arange(x.shape[dim])
              ret.append(dim_inds[tuple(broadcast_slice)])
      return tuple(ret)
docs: Calculate index values to properly broadcast index array within data array.
  
      See usage in interp.