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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_pourbaix_entries(self, chemsys):
 """ A helper function to get all entries necessary to generate a pourbaix diagram from the rest interface. Args: chemsys ([str]):
 A list of elements comprising the chemical system, e.g. ['Li', 'Fe'] """

        from pymatgen.analysis.pourbaix_diagram import PourbaixEntry, IonEntry
        from pymatgen.analysis.phase_diagram import PhaseDiagram
        from pymatgen.core.ion import Ion
        from pymatgen.entries.compatibility import \
            MaterialsProjectAqueousCompatibility

        pbx_entries = []

        # Get ion entries first, because certain ions have reference
        # solids that aren't necessarily in the chemsys (Na2SO4)
        url = '/pourbaix_diagram/reference_data/' + '-'.join(chemsys)
        ion_data = self._make_request(url)
        ion_ref_comps = [Composition(d['Reference Solid']) for d in ion_data]
        ion_ref_elts = list(itertools.chain.from_iterable(
            i.elements for i in ion_ref_comps))
        ion_ref_entries = self.get_entries_in_chemsys(
            list(set([str(e) for e in ion_ref_elts] + ['O', 'H'])),
            property_data=['e_above_hull'], compatible_only=False)
        compat = MaterialsProjectAqueousCompatibility("Advanced")
        ion_ref_entries = compat.process_entries(ion_ref_entries)
        ion_ref_pd = PhaseDiagram(ion_ref_entries)

        # position the ion energies relative to most stable reference state
        for n, i_d in enumerate(ion_data):
            ion_entry = IonEntry(Ion.from_formula(i_d['Name']), i_d['Energy'])
            refs = [e for e in ion_ref_entries
                    if e.composition.reduced_formula == i_d['Reference Solid']]
            if not refs:
                raise ValueError("Reference solid not contained in entry list")
            stable_ref = sorted(refs, key=lambda x: x.data['e_above_hull'])[0]
            rf = stable_ref.composition.get_reduced_composition_and_factor()[1]
            solid_diff = ion_ref_pd.get_form_energy(stable_ref) \
                         - i_d['Reference solid energy'] * rf
            elt = i_d['Major_Elements'][0]
            correction_factor = ion_entry.ion.composition[elt] \
                                / stable_ref.composition[elt]
            ion_entry.energy += solid_diff * correction_factor
            pbx_entries.append(PourbaixEntry(ion_entry, 'ion-{}'.format(n)))

        # Construct the solid pourbaix entries from filtered ion_ref entries
        extra_elts = set(ion_ref_elts) - {Element(s) for s in chemsys} \
                     - {Element('H'), Element('O')}
        for entry in ion_ref_entries:
            entry_elts = set(entry.composition.elements)
            # Ensure no OH chemsys or extraneous elements from ion references
            if not (entry_elts <= {Element('H'), Element('O')} or \
                            extra_elts.intersection(entry_elts)):
                # replace energy with formation energy, use dict to
                # avoid messing with the ion_ref_pd and to keep all old params
                form_e = ion_ref_pd.get_form_energy(entry)
                new_entry = deepcopy(entry)
                new_entry.uncorrected_energy = form_e
                new_entry.correction = 0.0
                pbx_entry = PourbaixEntry(new_entry)
                pbx_entries.append(pbx_entry)

        return pbx_entries