diff --git a/teacher_base.py b/teacher_base.py
index cd67bbd4316855bd917438132cf333de87923141..993c92b75f73be245b29671a0382b5c38846dc38 100644
--- a/teacher_base.py
+++ b/teacher_base.py
@@ -1,6 +1,7 @@
 import abc
 import itertools
-from typing import Dict, Hashable, List, Literal, Optional, Sequence, Tuple
+#from typing import Dict, Hashable, List, Literal, Optional, Sequence, Tuple
+from typing import Dict, Hashable, List, Optional, Sequence, Tuple
 
 import gurobipy as gp
 import numpy as np
@@ -46,7 +47,7 @@ class DRealTeacherBase(TeacherBase):
         ]
 
     def __init__(self, name: str,
-                 state_dim: int, perc_dim: int, ctrl_dim: int, norm_ord: Literal[1, 2, "inf"],
+                 state_dim: int, perc_dim: int, ctrl_dim: int, norm_ord,
                  delta: float = 0.001) -> None:
         self._norm_ord = norm_ord
         self._delta = delta
@@ -140,7 +141,7 @@ class GurobiTeacherBase(TeacherBase):
     TRIGVAR = {"vtype": gp.GRB.CONTINUOUS, "lb": -1.0, "ub": 1.0}
 
     def __init__(self, name: str,
-                 state_dim: int, perc_dim: int, ctrl_dim: int, norm_ord: Literal[1, 2, "inf"] = 2) -> None:
+                 state_dim: int, perc_dim: int, ctrl_dim: int, norm_ord = 2) -> None:
         super().__init__()
 
         self._gp_model = gp.Model(name)
@@ -225,7 +226,7 @@ class GurobiTeacherBase(TeacherBase):
 
 class SymPyTeacherBase(TeacherBase):
     def __init__(self, name: str,
-                 state_dim: int, perc_dim: int, ctrl_dim: int, norm_ord: Literal[1, 2, "inf"]) -> None:
+                 state_dim: int, perc_dim: int, ctrl_dim: int, norm_ord) -> None:
         self._norm_ord = norm_ord
 
         # Old state variables