code: def psi_l(l, b):
      n = l // 2
      v = (-b) ** n
      v *= gamma(n + 1.0 / 2) / gamma(2 * n + 3.0 / 2)
      v *= hyp1f1(n + 1.0 / 2, 2 * n + 3.0 / 2, -b)
      return v
  
imports: from warnings import warn
  import numpy
  from dipy.reconst.cache import Cache
  from dipy.reconst.multi_voxel import multi_voxel_fit
  from dipy.reconst.csdeconv import csdeconv
  from dipy.reconst.shm import real_sh_descoteaux_from_index
  from scipy.special import gamma, hyp1f1
  from dipy.core.geometry import cart2sphere
  from dipy.data import default_sphere
  from dipy.reconst.odf import OdfModel, OdfFit
  from scipy.optimize import leastsq
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 3 for calling a global function with example usage: psi_l(l, b) and returns: v