code: def test_time_index(N):
      domain = Domain(N, dx=[1.0] * len(N))
      params = jnp.ones((10,) + domain.N + (1,))
      field = OnGrid(params, domain)
  
      field_at_10 = field[10]
      assert jnp.allclose(field_at_10.params, jnp.ones(domain.N + (1,)))
  
imports: import pytest
  from jax import jit
  from jax import numpy
  from jax import random
  from jaxdf.discretization import FiniteDifferences, FourierSeries, OnGrid
  from jaxdf.geometry import Domain
  from jaxdf.operators import inverse
label_desc: Use image node_id 5 for calling a global function with example usage: test_time_index(N) without return types