'Scale image data by using ``BSCALE``/``BZERO``.
Call to this method will scale `data` and update the keywords of
``BSCALE`` and ``BZERO`` in the HDU\'s header.  This method should only
be used right before writing to the output file, as the data will be
scaled and is therefore not very usable after the call.
Parameters
type : str, optional
destination data type, use a string representing a numpy
dtype name, (e.g. ``\'uint8\'``, ``\'int16\'``, ``\'float32\'``
etc.).  If is `None`, use the current data type.
option : str, optional
How to scale the data: ``"old"`` uses the original ``BSCALE`` and
``BZERO`` values from when the data was read/created (defaulting to
1 and 0 if they don\'t exist). For integer data only, ``"minmax"``
uses the minimum and maximum of the data to scale. User-specified
``bscale``/``bzero`` values always take precedence.
bscale, bzero : int, optional
User-specified ``BSCALE`` and ``BZERO`` values'

def scale(self, type=None, option='old', bscale=None, bzero=None):

    self._scale_internal(type=type, option=option, bscale=bscale, bzero=bzero, blank=None)
