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.

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)