code: def spinflipandhop(slaves):
      
  
      Sdw = [csr_matrix(spin_gen(slaves, i, 0)) for i in range(slaves)]
      Sup = [mat.T for mat in Sdw]
  
      sfh = np.zeros_like(Sup[0])
      orbitals = slaves//2
      for n in range(orbitals):
          for m in range(n+1, orbitals):
              sfh += Sup[2*n  ] * Sdw[2*n + 1] * Sup[2*m + 1] * Sdw[2*m  ]
              sfh += Sup[2*n+1] * Sdw[2*n    ] * Sup[2*m    ] * Sdw[2*m+1]
  
              sfh += Sup[2*n] * Sup[2*n + 1] * Sdw[2*m] * Sdw[2*m+1]
              sfh += Sup[2*m] * Sup[2*m + 1] * Sdw[2*n] * Sdw[2*n+1]
  
      return sfh
docs: Calculates the interaction term of a spin flip and pair hopping