(self, i)
Performs the action of an annihilation operator.

        Examples
        ========

        >>> from sympy.physics.secondquant import BBra
        >>> b = BBra([1, 2])
        >>> b
        FockStateBosonBra((1, 2))
        >>> b.down(1)
        FockStateBosonBra((1, 1))
Performs the action of an annihilation operator.
Performs the action of an annihilation operator .
def down(self, i):
        """
        Performs the action of an annihilation operator.

        Examples
        ========

        >>> from sympy.physics.secondquant import BBra
        >>> b = BBra([1, 2])
        >>> b
        FockStateBosonBra((1, 2))
        >>> b.down(1)
        FockStateBosonBra((1, 1))
        """
        i = int(i)
        new_occs = list(self.args[0])
        if new_occs[i] == S.Zero:
            return S.Zero
        else:
            new_occs[i] = new_occs[i] - S.One
            return self.__class__(new_occs)
def down ( self , i ) : i = int ( i ) new_occs = list ( self . args [ 0 ] ) if new_occs [ i ] == S . Zero : return S . Zero else : new_occs [ i ] = new_occs [ i ] - S . One return self . __class__ ( new_occs )