'See `FITSDiff` for explanations of the initialization parameters.'

def __init__(self, a, b, numdiffs=10, rtol=0.0, atol=0.0, tolerance=None):

    self.numdiffs = numdiffs
    self.rtol = rtol
    self.atol = atol
    if (tolerance is not None):
        warnings.warn('"tolerance"    was    deprecated    in    version    2.0    and    will    be    removed    in    a    future    version.    Use    argument    "rtol"    instead.', AstropyDeprecationWarning)
        self.rtol = tolerance
    self.diff_dimensions = ()
    self.diff_pixels = []
    self.diff_ratio = 0
    self.diff_total = 0
    super(ImageDataDiff, self).__init__(a, b)
