class_docstr: This class defines a cropping operation:
  Removing ``2*border`` pixels from each spatial dim of the input,
  and return the spatially centred elements extracted from the input.
code: def __init__(self, border, name="crop"):
      super(CropLayer, self).__init__(name=name)
      self.border = border
  
file_path: NiftyNet/niftynet/layer/crop.py
imports: from __future__ import absolute_import, print_function
  import tensorflow
  from niftynet.layer import layer_util
  from niftynet.layer.base_layer import Layer
label_desc: Use image node_id 1 to create a new CropLayer object from inherited base classes: Layer with example: obj = CropLayer(border, name)