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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def offset(self, index=0):
 """Offset the camera pointing to be centred on a particular CCD."""

        eta = self._geometry[self.camera][index]["ra"]
        xi = self._geometry[self.camera][index]["dec"]
        ra = self.origin.ra - (eta/math.cos(self.dec.radian))*units.degree
        dec = self.origin.dec - xi * units.degree + 45 * units.arcsec
        self._coordinate = SkyCoord(ra, dec)