class_docstr: an axis spine -- the line noting the data area boundaries
  
  Spines are the lines connecting the axis tick marks and noting the
  boundaries of the data area. They can be placed at arbitrary
  positions. See function:`~matplotlib.spines.Spine.set_position`
  for more information.
  
  The default position is ``('outward',0)``.
  
  Spines are subclasses of class:`~matplotlib.patches.Patch`, and
  inherit much of their behavior.
  
  Spines draw a line, a circle, or an arc depending if
  function:`~matplotlib.spines.Spine.set_patch_line`,
  function:`~matplotlib.spines.Spine.set_patch_circle`, or
  function:`~matplotlib.spines.Spine.set_patch_arc` has been called.
  Line-like is the default.
docstr: get the spine transform
code: def get_spine_transform(self):
      """get the spine transform"""
      self._ensure_position_is_set()
      what, how = self._spine_transform
  
      if what == "data":
          # special case data based spine locations
          data_xform = self.axes.transScale + (
              how + self.axes.transLimits + self.axes.transAxes
          )
          if self.spine_type in ["left", "right"]:
              result = mtransforms.blended_transform_factory(
                  data_xform, self.axes.transData
              )
          elif self.spine_type in ["top", "bottom"]:
              result = mtransforms.blended_transform_factory(
                  self.axes.transData, data_xform
              )
          else:
              raise ValueError(
                  "unknown spine spine_type: %s" % self.spine_type
              )
          return result
  
      if self.spine_type in ["left", "right"]:
          base_transform = self.axes.get_yaxis_transform(which="grid")
      elif self.spine_type in ["top", "bottom"]:
          base_transform = self.axes.get_xaxis_transform(which="grid")
      else:
          raise ValueError(
              "unknown spine spine_type: %s" % self.spine_type
          )
  
      if what == "identity":
          return base_transform
      elif what == "post":
          return base_transform + how
      elif what == "pre":
          return how + base_transform
      else:
          raise ValueError("unknown spine_transform type: %s" % what)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import matplotlib
  from matplotlib.artist import allow_rasterization
  from matplotlib import docstring
  import matplotlib.transforms
  import matplotlib.patches
  import matplotlib.path
  import numpy
  import warnings
label_desc: Use image node_id 20 for calling the Spine obj's underlying member method code with example usage: obj.get_spine_transform() and returns: result, base_transform, unknown, unknown