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 testPlotly(self):
        plotter = VoltageProfilePlotter(xaxis="frac_x")
        plotter.add_electrode(self.ie_LTO, "LTO insertion")
        plotter.add_electrode(self.ce_FF, "FeF3 conversion")
        fig = plotter.get_plotly_figure()
        self.assertEqual(fig.layout.xaxis.title.text, "Atomic Fraction of Li")
        plotter = VoltageProfilePlotter(xaxis="x_form")
        plotter.add_electrode(self.ce_FF, "FeF3 conversion")
        fig = plotter.get_plotly_figure()
        self.assertEqual(fig.layout.xaxis.title.text, "x in Li<sub>x</sub>FeF3")

        plotter.add_electrode(self.ie_LTO, "LTO insertion")
        fig = plotter.get_plotly_figure()
        self.assertEqual(fig.layout.xaxis.title.text, "x Workion Ion per Host F.U.")