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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 inspect(self, **kwargs):
 """ Plot the evolution of the structural relaxation with matplotlib. Args: what: Either "hist" or "scf". The first option (default) extracts data from the HIST file and plot the evolution of the structural parameters, forces, pressures and energies. The second option, extracts data from the main output file and plot the evolution of the SCF cycles (etotal, residuals, etc). Returns: `matplotlib` figure, None if some error occurred. """

        what = kwargs.pop("what", "hist")

        if what == "hist":
            # Read the hist file to get access to the structure.
            with self.open_hist() as hist:
                return hist.plot(**kwargs) if hist else None

        elif what == "scf":
            # Get info on the different SCF cycles
            relaxation = abiinspect.Relaxation.from_file(self.output_file.path)
            if "title" not in kwargs: kwargs["title"] = str(self)
            return relaxation.plot(**kwargs) if relaxation is not None else None

        else:
            raise ValueError("Wrong value for what %s" % what)