docstr: Frees the resources allocated during initialization
          
docstr_tok: ["Frees","the","resources","allocated","during","initialization"]
code: def free_iteration(self):
      r"""Frees the resources allocated during initialization"""
      del self.factors
      del self.gradient_moving
      del self.gradient_static
  
imports: import abc
  import numpy
  from numpy import gradient
  from scipy import ndimage
  from dipy.align import vector_fields
  from dipy.align import sumsqdiff
  from dipy.align import crosscorr
  from dipy.align import expectmax
  from dipy.align import floating
label_desc: Use image node_id 4 for calling the CCMetric obj's underlying member method code with example usage: obj.free_iteration() without return types