'Return X,Y, the coordinate arrays for the colorbar pcolormesh.
These are suitable for a vertical colorbar; swapping and
transposition for a horizontal colorbar are done outside
this function.'

def _mesh(self):

    x = np.array([1.0, 2.0])
    if (self.spacing == u'uniform'):
        y = self._uniform_y(len(self._boundaries))
    else:
        y = self._boundaries
    self._y = y
    (X, Y) = np.meshgrid(x, y)
    return (X, Y)
