How to modify a BJT's parameters?

I have checked the API documentation but didn’t find an answer or example.

circuit = Circuit(‘Transistor’)
source = circuit.SinusoidalVoltageSource(‘in’, ‘in’, circuit.gnd, amplitude=.5@u_V, frequency=1@u_kHz)
Vpower = circuit.V(‘power’, 5, circuit.gnd, 15@u_V)
R1 = circuit.R(1, 5, 2, 100@u_kΩ)
RC = circuit.R(‘C’, 5, 4, 10@u_kΩ)
C2 = circuit.C(2, 4, ‘out’, 10@u_uF)
C1 = circuit.C(1, ‘in’, 2, 10@u_uF)

Q1= circuit.BJT(1, 4, 2, 3, model=‘bjt’) # Q is mapped to BJT !
circuit.model(‘bjt’, ‘npn’, bf=80, cjc=pico(5), rb=100) #rb: Base Resistor

How to change BJT’s rb in this case?