TypeError: unsupported operand type(s) for ** or pow(): 'int' and 'LpVariable'

Question

sorry I am new to Python pulp. I encounter the error TypeError: unsupported operand type(s) for ** or pow(): 'int' and 'LpVariable' when running the script.

from pulp import *

problem = LpProblem('CASA Optimization', LpMaximize)

A1 = LpVariable('Option A1', lowBound=0 , cat=LpInteger)
A2 = LpVariable('Option A2', lowBound=0 , cat=LpInteger)
B1 = LpVariable('Option B1', lowBound=0 , cat=LpInteger)
C1 = LpVariable('Option C1', lowBound=0 , cat=LpInteger)
C2 = LpVariable('Option C2', lowBound=0 , cat=LpInteger)
D1 = LpVariable('Option D1', lowBound=0 , cat=LpInteger)
D2 = LpVariable('Option D2', lowBound=0 , cat=LpInteger)
E1 = LpVariable('Option E1', lowBound=0 , cat=LpInteger)
E2 = LpVariable('Option E2', lowBound=0 , cat=LpInteger)

problem += 15*A1 + 18*A2 + 9.6*B1 + 9.5*C1 + 17*C2 + 1*D1 + 1.5*D2 + 0.9*E1 + 0.6*E2 , 'Objective Function'
#Constraints
problem += 100*A1 + 130*A2 + 80*B1 + 80*C1 + 130*C2 + 10*D1 + 20*D2 + 8*E1 + 5*E2 <= 200 , 'Total Fund Constrain'
problem += 1**A1 + 1**A2 <= 1, 'Probability Constrain'
problem += 1**B1 <= 1, 'Probability Constrain'
problem += 1**C1 + 1**C2 <= 1, 'Probability Constrain'
problem += 1**D1 + 1**D2 <= 1, 'Probability Constrain'
problem += 1**E1 + 1**E2 <= 1, 'Probability Constrain'

problem.solve()
print("A1 value: ", A1.varValue)
print("A2 value: ", A2.varValue)
print("B1 value: ", B1.varValue)
print("C1 value: ", C1.varValue)
print("C2 value: ", C2.varValue)
print("D1 value: ", D1.varValue)
print("D2 value: ", D2.varValue)
print("E1 value: ", E1.varValue)
print("E2 value: ", E2.varValue)

Please advise me how to solve the issue