code: def odf_sum(odf):
      return np.sum(odf)
  
imports: import numpy
  from dipy.reconst.odf import OdfModel, OdfFit
  from dipy.reconst.cache import Cache
  import warnings
  from dipy.reconst.multi_voxel import multi_voxel_fit
label_desc: Use image node_id 10 for calling a global function with example usage: odf_sum(odf) and returns: np