code: def sticks_and_ball_dummies(gtab):
      sb_dummies = {}
      S, sticks = sticks_and_ball(
          gtab,
          d=0.0015,
          S0=100,
          angles=[(0, 0)],
          fractions=[100],
          snr=None,
      )
      sb_dummies["1fiber"] = (S, sticks)
      S, sticks = sticks_and_ball(
          gtab,
          d=0.0015,
          S0=100,
          angles=[(0, 0), (90, 0)],
          fractions=[50, 50],
          snr=None,
      )
      sb_dummies["2fiber"] = (S, sticks)
      S, sticks = sticks_and_ball(
          gtab,
          d=0.0015,
          S0=100,
          angles=[(0, 0), (90, 0), (90, 90)],
          fractions=[33, 33, 33],
          snr=None,
      )
      sb_dummies["3fiber"] = (S, sticks)
      S, sticks = sticks_and_ball(
          gtab,
          d=0.0015,
          S0=100,
          angles=[(0, 0), (90, 0), (90, 90)],
          fractions=[0, 0, 0],
          snr=None,
      )
      sb_dummies["isotropic"] = (S, sticks)
      return sb_dummies
  
file_path: dipy/dipy/reconst/tests/test_dsi.py
imports: import numpy
  from numpy.testing import assert_equal, assert_almost_equal, assert_raises
  from dipy.data import get_fnames, dsi_voxels, default_sphere
  from dipy.reconst.dsi import DiffusionSpectrumModel
  from dipy.reconst.odf import gfa
  from dipy.direction.peaks import peak_directions
  from dipy.sims.voxel import sticks_and_ball
  from dipy.core.gradients import gradient_table
  from dipy.core.subdivide_octahedron import create_unit_sphere
  from dipy.core.sphere_stats import angular_similarity
label_desc: Use image node_id 4 for calling a global function with example usage: sticks_and_ball_dummies(gtab) and returns: sb_dummies