docstr: Deformation field to transform an image in the backward direction
  
  Returns the deformation field that must be used to warp an image under
  this transformation in the backward direction (note the 'is_inverse'
  flag).
code: def get_backward_field(self):
      """Deformation field to transform an image in the backward direction
  
      Returns the deformation field that must be used to warp an image under
      this transformation in the backward direction (note the 'is_inverse'
      flag).
      """
      if self.is_inverse:
          return self.forward
      else:
          return self.backward
  
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 4 for calling the DiffeomorphicMap obj's underlying member method code with example usage: obj.get_backward_field() and returns: self, self