How to use the hyperspy.misc.eds.utils._parse_only_lines function in hyperspy

['Al_Ka', 'C_Ka', 'Cu_Ka', 'Mn_Ka', 'Zr_La']

        >>> s = hs.datasets.example_signals.EDS_SEM_Spectrum()
        >>> s.add_lines()
        >>> print(s.metadata.Sample.xray_lines)
        >>> s.add_lines(['Cu_Ka'])
        >>> print(s.metadata.Sample.xray_lines)
        ['Al_Ka', 'C_Ka', 'Cu_La', 'Mn_La', 'Zr_La']
        ['Al_Ka', 'C_Ka', 'Cu_Ka', 'Cu_La', 'Mn_La', 'Zr_La']

        See also
        --------
        set_lines, add_elements, set_elements

        """
        only_lines = utils_eds._parse_only_lines(only_lines)
        if "Sample.xray_lines" in self.metadata:
            xray_lines = set(self.metadata.Sample.xray_lines)
        else:
            xray_lines = set()
        # Define the elements which Xray lines has been customized
        # So that we don't attempt to add new lines automatically
        elements = set()
        for line in xray_lines:
            elements.add(line.split("_")[0])
        for line in lines:
            try:
                element, subshell = line.split("_")
            except ValueError:
                raise ValueError(
                    "Invalid line symbol. "
                    "Please provide a valid line symbol e.g. Fe_Ka")

['Al_Ka', 'C_Ka', 'Cu_Ka', 'Mn_Ka', 'Zr_La']

        >>> s = hs.datasets.example_signals.EDS_SEM_Spectrum()
        >>> s.add_lines()
        >>> print(s.metadata.Sample.xray_lines)
        >>> s.add_lines(['Cu_Ka'])
        >>> print(s.metadata.Sample.xray_lines)
        ['Al_Ka', 'C_Ka', 'Cu_La', 'Mn_La', 'Zr_La']
        ['Al_Ka', 'C_Ka', 'Cu_Ka', 'Cu_La', 'Mn_La', 'Zr_La']

        See also
        --------
        set_lines, add_elements, set_elements

        """
        only_lines = utils_eds._parse_only_lines(only_lines)
        if "Sample.xray_lines" in self.metadata:
            xray_lines = set(self.metadata.Sample.xray_lines)
        else:
            xray_lines = set()
        # Define the elements which Xray lines has been customized
        # So that we don't attempt to add new lines automatically
        elements = set()
        for line in xray_lines:
            elements.add(line.split("_")[0])
        for line in lines:
            try:
                element, subshell = line.split("_")
            except ValueError:
                raise ValueError(
                    "Invalid line symbol. "
                    "Please provide a valid line symbol e.g. Fe_Ka")

elements : list of strings
            A list containing the symbol of the chemical elements.
        only_one : bool
            If False, add all the lines of each element in the data spectral
            range. If True only add the line at the highest energy
            above an overvoltage of 2 (< beam energy / 2).
        only_lines : {None, list of strings}
            If not None, only the given lines will be returned.

        Returns
        -------
        list of X-ray lines alphabetically sorted

        """

        only_lines = utils_eds._parse_only_lines(only_lines)
        beam_energy = self._get_beam_energy()
        lines = []
        elements = [el if isinstance(el, str) else el.decode()
                    for el in elements]
        for element in elements:
            # Possible line (existing and excited by electron)
            element_lines = []
            for subshell in list(elements_db[element]['Atomic_properties'
                                                      ]['Xray_lines'].keys()):
                if only_lines and subshell not in only_lines:
                    continue
                element_lines.append(element + "_" + subshell)
            element_lines = self._get_xray_lines_in_spectral_range(
                element_lines)[0]
            if only_one and element_lines:
                # Choose the best line

elements : list of strings
            A list containing the symbol of the chemical elements.
        only_one : bool
            If False, add all the lines of each element in the data spectral
            range. If True only add the line at the highest energy
            above an overvoltage of 2 (< beam energy / 2).
        only_lines : {None, list of strings}
            If not None, only the given lines will be returned.

        Returns
        -------
        list of X-ray lines alphabetically sorted

        """

        only_lines = utils_eds._parse_only_lines(only_lines)
        beam_energy = self._get_beam_energy()
        lines = []
        elements = [el if isinstance(el, str) else el.decode()
                    for el in elements]
        for element in elements:
            # Possible line (existing and excited by electron)
            element_lines = []
            for subshell in list(elements_db[element]['Atomic_properties'
                                                      ]['Xray_lines'].keys()):
                if only_lines and subshell not in only_lines:
                    continue
                element_lines.append(element + "_" + subshell)
            element_lines = self._get_xray_lines_in_spectral_range(
                element_lines)[0]
            if only_one and element_lines:
                # Choose the best line

def _plot_xray_lines(self, xray_lines=False, only_lines=("a", "b"),
                         only_one=False, background_windows=None,
                         integration_windows=None):
        if xray_lines is not False or\
                background_windows is not None or\
                integration_windows is not None:
            if xray_lines is False:
                xray_lines = True
            only_lines = utils_eds._parse_only_lines(only_lines)
            if xray_lines is True or xray_lines == 'from_elements':
                if 'Sample.xray_lines' in self.metadata \
                        and xray_lines != 'from_elements':
                    xray_lines = self.metadata.Sample.xray_lines
                elif 'Sample.elements' in self.metadata:
                    xray_lines = self._get_lines_from_elements(
                        self.metadata.Sample.elements,
                        only_one=only_one,
                        only_lines=only_lines)
                else:
                    raise ValueError(
                        "No elements defined, set them with `add_elements`")
            xray_lines, xray_not_here = self._get_xray_lines_in_spectral_range(
                xray_lines)
            for xray in xray_not_here:
                _logger.warn("%s is not in the data energy range." % xray)

elements : list of strings
            A list containing the symbol of the chemical elements.
        only_one : bool
            If False, add all the lines of each element in the data spectral
            range. If True only add the line at the highest energy
            above an overvoltage of 2 (< beam energy / 2).
        only_lines : {None, list of strings}
            If not None, only the given lines will be returned.

        Returns
        -------
        list of X-ray lines alphabetically sorted

        """

        only_lines = utils_eds._parse_only_lines(only_lines)
        beam_energy = self._get_beam_energy()
        lines = []
        elements = [el if isinstance(el, str) else el.decode()
                    for el in elements]
        for element in elements:
            # Possible line (existing and excited by electron)
            element_lines = []
            for subshell in list(elements_db[element]['Atomic_properties'
                                                      ]['Xray_lines'].keys()):
                if only_lines and subshell not in only_lines:
                    continue
                element_lines.append(element + "_" + subshell)
            element_lines = self._get_xray_lines_in_spectral_range(
                element_lines)[0]
            if only_one and element_lines:
                # Choose the best line