code: def basic_field_3(nx=10, ny=10, nz=10):
      xyz = np.reshape(np.indices((nx, ny, nz)), (3, nx * ny * nz)).T
      toto = xyz - np.array([5, 5, 5])
      data = np.abs(np.sum(toto**2, 1) - 11)
      myfield = field_from_graph_and_data(
          wgraph_from_3d_grid(xyz, 26), data
      )
      return myfield
  
imports: import numpy
  import numpy.random
  from numpy.testing import assert_array_equal
  from ..field import field_from_coo_matrix_and_data, field_from_graph_and_data
  from ..graph import wgraph_from_3d_grid
label_desc: Use image node_id 4 for calling a global function with example usage: basic_field_3(nx, ny, nz) and returns: myfield