class_docstr: Fock state bra for a fermionic mode.
  
  Parameters
  ==========
  
  n : Number
      The Fock state number.
class_docstr_tok: ["Fock","state","bra","for","a","fermionic","mode",".","Parameters","==========","n",":","Number","The","Fock","state","number","."]
code: def __new__(cls, n):
      if n not in (0, 1):
          raise ValueError("n must be 0 or 1")
      return Bra.__new__(cls, n)
  
imports: from sympy.core.numbers import Integer
  from sympy.core.singleton import S
  from sympy.physics.quantum import Operator
  from sympy.physics.quantum import HilbertSpace, Ket, Bra
  from sympy.functions.special.tensor_functions import KroneckerDelta
label_desc: Use image node_id 1 for calling the FermionFockBra obj's underlying member method code with example usage: obj.__new__(cls, n) and returns: Bra