def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def __draw_ellipse(ax, x, y, angle, width, height, color):
        if (width > 0.0) and (height > 0.0):
            ax.plot(x, y, color=color, marker='x', markersize=6)
            ellipse = patches.Ellipse((x, y), width, height, alpha=0.2, angle=-angle, linewidth=2, fill=True, zorder=2, color=color)
            ax.add_patch(ellipse)