docs: def _latex_(self):
          r"""The LaTeX routine for states.
  
          >>> State("Rb",85,5,0,1/Integer(2))._latex_()
          '^{85}\\mathrm{Rb}\\ 5S_{1/2}'
  
          >>> State("Rb",85,5,0,1/Integer(2),2)._latex_()
          '^{85}\\mathrm{Rb}\\ 5S_{1/2}^{2}'
  
          >>> State("Rb",85,5,0,1/Integer(2),2,2)._latex_()
          '^{85}\\mathrm{Rb}\\ 5S_{1/2}^{2,2}'
  
          """
          if self.l == 0: l = 'S'
          elif self.l == 1: l = 'P'
          elif self.l == 2: l = 'D'
          elif self.l == 3: l = 'F'
          else: l = str(self.l)
  
          if self.f is None:
              s = '^{'+str(self.isotope)+'}\\mathrm{'+self.element+'}\\ '
              s += str(self.n)+l+'_{'+str(self.j)+'}'
          else:
              s = '^{'+str(self.isotope)+'}\\mathrm{'+self.element+'}\\ '
              s += str(self.n)+l+'_{'+str(self.j)+'}^{'+str(self.f)+'}'
  
          if self.m is not None:
              s = s[:-1] + ','+str(self.m)+'}'
  
          return s