code: def test_fermion_states():
      c = FermionOp("c")
  
      # Fock states
      assert (FermionFockBra(0) * FermionFockKet(1)).doit() == 0
      assert (FermionFockBra(1) * FermionFockKet(1)).doit() == 1
  
      assert qapply(c * FermionFockKet(1)) == FermionFockKet(0)
      assert qapply(c * FermionFockKet(0)) == 0
  
      assert qapply(Dagger(c) * FermionFockKet(0)) == FermionFockKet(1)
      assert qapply(Dagger(c) * FermionFockKet(1)) == 0
  
file_path: sympy/sympy/physics/quantum/tests/test_fermion.py
imports: from pytest import raises
  import sympy
  from sympy.physics.quantum import Dagger, AntiCommutator, qapply
  from sympy.physics.quantum.fermion import FermionOp
  from sympy.physics.quantum.fermion import FermionFockKet, FermionFockBra
  from sympy import Symbol
label_desc: Use image node_id 2 for calling a global function with example usage: test_fermion_states() without return types