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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 init_return(self, ret_type):
 """Specify the return type. Note that this will also construct the '~fermipy.castro.Interpolator' object for the requested return type. """

        if self._ret_type == ret_type:
            return
        if ret_type == "straight":
            self._interp = self._lnlfn.interp
        if ret_type == "profile":
            self._profile_loglike_spline(self._lnlfn.interp.x)
            #self._profile_loglike(self._lnlfn.interp.x)
            self._interp = self._prof_interp
        elif ret_type == "marginal":
            self._marginal_loglike(self._lnlfn.interp.x)
            self._interp = self._marg_interp
        elif ret_type == "posterior":
            self._posterior(self._lnlfn.interp.x)
            self._interp = self._post_interp
        else:
            raise ValueError("Did not recognize return type %s" % ret_type)

        self._ret_type = ret_type