pycasbin: ABAC eval not working with empty dict

Model:

[request_definition]
r = sub, obj, type, act 

[policy_definition]
p = rule, type, act

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = eval(p.rule) && r.type == p.type && r.act == p.act

Policy:

p, r.sub.admin == True, user, delete
p, r.sub.identifier == r.obj.identifier, user, read

When attempting to eval the following:

abac_enforcer = casbin.Enforcer(
    str(file_path(...)), str(file_path(...))

if abac_enforcer.enforce({"admin": False}, {}, "user", "delete"):
        return True

Raises the following:

/simpleeval.py", line 481, in _eval_attribute
    raise AttributeDoesNotExist(node.attr, self.expr)
simpleeval.AttributeDoesNotExist: ('identifier', '(r_sub.identifier == r_obj.identifier) and r_type == p_type and r_act == p_act')

I attempted this within the online editor and it works fine. Sorry if I’m missing something. New PyCasbin user here!