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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 _build_src_index(self):
 """Build an indices for fast lookup of a source given its name or coordinates."""


        self._srcs = sorted(self._srcs, key=lambda t: t['offset'])
        nsrc = len(self._srcs)
        radec = np.zeros((2, nsrc))

        for i, src in enumerate(self._srcs):
            radec[:, i] = src.radec

        self._src_skydir = SkyCoord(ra=radec[0], dec=radec[1], unit=u.deg)
        self._src_radius = self._src_skydir.separation(self.skydir)