def METHOD_NAME(self, isostring):
    """
    Returns the nuclide object given an identifying string
    isostring which consists of:
    [A]-[Abbreviation]
    E.g. "4-He", "7-li", etc.
    """
    try:
        a, abb = tuple(isostring.split('-'))
    except ValueError:
        print('ERROR: Supply an isotope string in the form "4-He"')
        raise
    a = int(a)
    abb = abb.strip().lower()
    for nuc in self.nuclides:
        if nuc.a == a and nuc.element.lower() == abb:
            return nuc
    print('ERROR: Could not find a nuclide by the specification {}'.format(isostring))