code: def plot_xtb(fignum, XTB, Bs, e, f):
      
      plt.figure(num=fignum)
      plt.xlabel('Temperature (K)')
      plt.ylabel('Susceptibility (m^3/kg)')
      k = 0
      Blab = []
      for field in XTB:
          T, X = [], []
          for xt in field:
              X.append(xt[0])
              T.append(xt[1])
          plt.plot(T, X)
          plt.text(T[-1], X[-1], '%8.2e' % (Bs[k]) + ' T')
  #        Blab.append('%8.1e'%(Bs[k])+' T')
          k += 1
      plt.title(e + ': f = ' + '%i' % (int(f)) + ' Hz')
docs: function to plot series of chi measurements as a function of temperature, holding frequency constant and varying B