code: def get_ongrid_fields():
      domain = geometry.Domain((1,), (1.0,))
      a = OnGrid(jnp.asarray([1.0]), domain)
      b = OnGrid(jnp.asarray([2.0]), domain)
      return a, b
  
file_path: jaxdf/tests/test_core.py
imports: import jax
  import numpy
  import pytest
  from jax import jit
  from jax import numpy
  from jaxdf import *
  from jaxdf.signatures import SignatureError
label_desc: Use image node_id 1 for calling a global function with example usage: get_ongrid_fields() and returns: a,  b