code: def _plot_transform_pairs(fCI, r, k, axes, tit):
      r
  
      # Plot lhs
      plt.sca(axes[0])
      plt.title('|' + tit + ' lhs|')
      for f in fCI:
          if f.name == 'j2':
              lhs = f.lhs(k)
              plt.loglog(k, np.abs(lhs[0]), lw=2, label='j0')
              plt.loglog(k, np.abs(lhs[1]), lw=2, label='j1')
          else:
              plt.loglog(k, np.abs(f.lhs(k)), lw=2, label=f.name)
      if tit != 'fC':
          plt.xlabel('l')
      plt.legend(loc='best')
  
      # Plot rhs
      plt.sca(axes[1])
      plt.title('|' + tit + ' rhs|')
  
      # Transform pair rhs
      for f in fCI:
          if tit == 'fC':
              plt.loglog(r, np.abs(f.rhs), lw=2, label=f.name)
          else:
              plt.loglog(r, np.abs(f.rhs(r)), lw=2, label=f.name)
  
      # Transform with Key
      for f in fCI:
          if f.name[1] in ['0', '1', '2']:
              filt = j0j1filt()
          else:
              filt = sincosfilt()
          kk = filt.base/r[:, None]
          if f.name == 'j2':
              lhs = f.lhs(kk)
              kr0 = np.dot(lhs[0], getattr(filt, 'j0'))/r
              kr1 = np.dot(lhs[1], getattr(filt, 'j1'))/r**2
              kr = kr0+kr1
          else:
              kr = np.dot(f.lhs(kk), getattr(filt, f.name))/r
  
          plt.loglog(r, np.abs(kr), '-.', lw=2, label=filt.name)
  
      if tit != 'fC':
          plt.xlabel('r')
  
      plt.legend(loc='best')
docs: r"""Plot the input transform pairs.