'Returns a dict whose keys are spine names and values are
Line2D or Patch instances. Each element is used to draw a
spine of the axes.
In the standard axes, this is a single line segment, but in
other projections it may not be.
.. note::
Intended to be overridden by new projection types.'

def _gen_axes_spines(self, locations=None, offset=0.0, units=u'inches'):

    return OrderedDict([(u'left', mspines.Spine.linear_spine(self, u'left')), (u'right', mspines.Spine.linear_spine(self, u'right')), (u'bottom', mspines.Spine.linear_spine(self, u'bottom')), (u'top', mspines.Spine.linear_spine(self, u'top'))])
