code: def _kappa_odf(zeta, n, l):
      return np.sqrt(
          (gamma(l / 2.0 + 1.5) ** 2 * gamma(n + 1.5) * 2 ** (l + 3))
          / (
              16
              * np.pi**3
              * zeta**1.5
              * factorial(n - l)
              * gamma(l + 1.5) ** 2
          )
      )
  
imports: from warnings import warn
  from math import factorial
  import numpy
  from scipy.special import genlaguerre, gamma, hyp2f1
  from dipy.reconst.cache import Cache
  from dipy.reconst.multi_voxel import multi_voxel_fit
  from dipy.reconst.shm import real_sh_descoteaux_from_index
  from dipy.core.geometry import cart2sphere
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 6 for calling a global function with example usage: _kappa_odf(zeta, n, l) and returns: np