使用pult提示错误：UserWarning: Spaces are not permitted in the name. Converted to ‘_‘

 jupyter notebook使用pulp库提示错误，但是在vscode中能正常执行：

C:\Program Files (x86)\Python311\Lib\site-packages\pulp\pulp.py:1352: UserWarning: Spaces are not permitted in the name. Converted to '_'
  warnings.warn("Spaces are not permitted in the name. Converted to '_'")

运行如下代码：

import pulp
dealers = ["x","y","z"]
variables_costs = {"x":500,
                   "y":350,
                   "z":450}
fix_costs = {"x":4000,"y":2000,"z":6000}
quantities = pulp.LpVariable.dicts("quantity",dealers,lowBound=0,cat=pulp.LpInteger)
is_orders = pulp.LpVariable.dicts("orders",dealers,cat=pulp.LpBinary)
model = pulp.LpProblem("problem",pulp.LpMinimize)
model += sum([variables_costs[i] * quantities[i] + fix_costs[i] * is_orders[i] for i in dealers]),"Minimize portfolio cost"
model += sum([quantities[i] for i in dealers]) == 150,"Total contracts required"
model += is_orders["x"]*30<= quantities["x"] <= is_orders["x"]*100,"Boundary of total volume of x"
model += is_orders["y"]*30<= quantities["y"] <= is_orders["y"]*90, "Boundary of total volume of y"
model += is_orders["z"]*30<= quantities["z"] <= is_orders["z"]*70, "Boundary of total volume of z"
model.solve()