def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
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)