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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 functional(self, fnct, x, y, sd=None, wt=1.0, mxit=50, fid=0):
 """Make a non-linear least squares solution. This will make a non-linear least squares solution for the points through the ordinates at the abscissa values, using the specified `fnct`. Details can be found in the :meth:`linear` description. :param fnct: the functional to fit :param x: the abscissa values :param y: the ordinate values :param sd: standard deviation of equations (one or more values used cyclically) :param wt: an optional alternate for `sd` :param mxit: the maximum number of iterations :param fid: the id of the sub-fitter (numerical) """

        self._fit(fitfunc="functional", fnct=fnct, x=x, y=y, sd=sd, wt=wt,
                  mxit=mxit, fid=fid)