def _reconstruct_isotope_symbol(element: str, mass_numb: Integral) -> str:
"""
Receive a `str` representing an atomic symbol and an
`int` representing a mass number. Return the isotope symbol
or `None` if no mass number information is available. Raises an
`~plasmapy.utils.InvalidParticleError` for isotopes that have
not yet been discovered.
"""
if mass_numb is not None:
isotope = f"{element}-{mass_numb}"
if isotope == 'H-2':
isotope = 'D'
elif isotope == 'H-3':
isotope = 'T'
if isotope not in _Isotopes.keys():
raise InvalidParticleError(
f"The string '{isotope}' does not correspond to "
f"a valid isotope.")
else:
isotope = None
return isotope
def known_isotopes_for_element(argument):
element = atomic_symbol(argument)
isotopes = []
for isotope in _Isotopes.keys():
if element + '-' in isotope and isotope[0:len(element)] == element:
isotopes.append(isotope)
if element == 'H':
isotopes.insert(1, 'D')
isotopes.insert(2, 'T')
mass_numbers = [mass_number(isotope) for isotope in isotopes]
sorted_isotopes = [mass_number for (isotope, mass_number) in
sorted(zip(mass_numbers, isotopes))]
return sorted_isotopes