NF=2
NB=0
IndexDn={0}
IndexUp={1}

psi0=NewWavefunction(NF,NB,{{"10",1}})
psi1=NewWavefunction(NF,NB,{{"01",1}})

OppSx   = NewOperator("Sx"   ,NF,IndexUp,IndexDn)
OppSy   = NewOperator("Sy"   ,NF,IndexUp,IndexDn)
OppSz   = NewOperator("Sz"   ,NF,IndexUp,IndexDn)

print("The expectation value of a single state")
print(Braket(psi0,OppSz,psi0))

print("The expectation value of two states with a single state")
print(Braket(psi0,OppSx,{psi0,psi1}))

-- note that I made one list of length 3, the other of length 2 so that the order is clear
print("The expectation value of a three states with two other states")
print(Braket({psi0,psi1},OppSy,{psi0,psi1,psi1}))