InSwitchDefList : InSwitchDef
                    | InSwitchDefList InSwitchDef

def p_InSwitchDefList(p):
    '''
    InSwitchDefList : InSwitchDef
                    | InSwitchDefList InSwitchDef
   '''
    if len(p) <= 2:
        p[0] = InSwitchDefList(None, p[1])
    else:
        p[0] = InSwitchDefList(p[1], p[2])