docstr: Starts the metric optimization
  
  This is the main function each specialized class derived from this must
  implement. Upon completion, the deformation field must be available
  from the forward transformation model.
code: def optimize(self):
      """Starts the metric optimization
  
      This is the main function each specialized class derived from this must
      implement. Upon completion, the deformation field must be available
      from the forward transformation model.
      """
  
imports: import logging
  import abc
  import numpy
  import numpy.linalg
  import nibabel
  from nibabel.streamlines import ArraySequence
  from dipy.align import vector_fields
  from dipy.align import floating
  from dipy.align import VerbosityLevels
  from dipy.align import Bunch
  from dipy.align.scalespace import ScaleSpace
label_desc: Use image node_id 3 for calling the DiffeomorphicRegistration obj's underlying member method code with example usage: obj.optimize() without return types