class_docstr: Affine warp constraints class.
  
  `AffineWarpConstraints` allow for
  very succinct definitions of constraints on
  the values of entries in affine transform matrices.
docstr: Returns the list of constraints
  for the i-th row of the affine matrix.
docstr_tok: ["Returns","the","list","of","constraints","for","the","i-th","row","of","the","affine","matrix","."]
code: def __getitem__(self, i):
      """
      Returns the list of constraints
      for the i-th row of the affine matrix.
      """
      return self._constraints[i]
  
imports: from __future__ import absolute_import, division, print_function
  from itertools import chain
  import numpy
  import tensorflow
  from niftynet.layer.base_layer import Layer, LayerFromCallable, Invertible
label_desc: Use image node_id 6 for calling the AffineWarpConstraints obj's underlying member method code with example usage: obj.__getitem__(i) and returns: self