'aux_trans : a transform from the source (curved) coordinate to
target (rectilinear) coordinate. An instance of MPL\'s Transform
(inverse transform should be defined) or a tuple of two callable
objects which defines the transform and its inverse. The callables
need take two arguments of array of source coordinates and
should return two target coordinates:
e.g., x2, y2 = trans(x1, y1)'

def __init__(self, aux_trans, extremes, grid_locator1=None, grid_locator2=None, tick_formatter1=None, tick_formatter2=None):

    self._old_values = None
    self._extremes = extremes
    extreme_finder = ExtremeFinderFixed(extremes)
    super(GridHelperCurveLinear, self).__init__(aux_trans, extreme_finder, grid_locator1=grid_locator1, grid_locator2=grid_locator2, tick_formatter1=tick_formatter1, tick_formatter2=tick_formatter2)
