diff --git a/ethosu/vela/tensor.py b/ethosu/vela/tensor.py
index 783f459..38b0e43 100644
--- a/ethosu/vela/tensor.py
+++ b/ethosu/vela/tensor.py
@@ -269,9 +269,10 @@
         return np.subtract(values, self.zero_point) * self.scale_f32
 
     def is_scaling_equal(self, other: Optional["QuantizationParameters"]) -> bool:
-        # quantisation parameter scaling is not equal if 'other' is None because
-        # it implies that the tensor it belongs to is not quantised. otherwise,
-        # it depends upon whether the scale and zero point are equal
+        """
+        Returns True if the scale and zero point of self and other are equal. If other is None then the scaling is
+        not considered equal because the tensor is assumed to not be quantised and False will be returned
+        """
 
         if not isinstance(other, QuantizationParameters):
             return False
@@ -279,12 +280,13 @@
         return self.scale_f32 == other.scale_f32 and self.zero_point == other.zero_point
 
     def is_valid(self) -> bool:
-        # quantisation parameters are consider valid if they have a scale and zero point
+        """Return True if the quantisation parameters have a scale and zero point"""
 
         return self.scale_f32 is not None and self.zero_point is not None
 
     def is_per_axis(self) -> bool:
         """Returns True if either the scale, zero point, minimum or maximum values have more than one value"""
+
         for attr in ("scale_f32", "zero_point", "min", "max"):
             if np.size(getattr(self, attr)) > 1:
                 return True
diff --git a/ethosu/vela/tflite_mapping.py b/ethosu/vela/tflite_mapping.py
index a5f7fa2..e12267f 100644
--- a/ethosu/vela/tflite_mapping.py
+++ b/ethosu/vela/tflite_mapping.py
@@ -950,13 +950,11 @@
 
 BUILTIN_OPERATOR_UNKNOWN = "UNKNOWN"
 
-
-def builtin_type_name(builtin):
-    return next(k for k, v in vars(BuiltinOperator).items() if v == builtin)
+builtin_operator_name_map = {v: k for k, v in vars(BuiltinOperator).items()}
 
 
-def optype_to_builtintype(op_type):
+def optype_to_builtintype(op_type: Op):
     if op_type in builtin_operator_inv_map:
-        return builtin_type_name(builtin_operator_inv_map[op_type][0])
+        return builtin_operator_name_map[builtin_operator_inv_map[op_type][0]]
     else:
         return BUILTIN_OPERATOR_UNKNOWN
diff --git a/ethosu/vela/tosa_mapping.py b/ethosu/vela/tosa_mapping.py
index 6710787..f635e4a 100644
--- a/ethosu/vela/tosa_mapping.py
+++ b/ethosu/vela/tosa_mapping.py
@@ -323,14 +323,12 @@
 
 tosa_operator_inv_map = {v[0]: (k, v[1]) for k, v in tosa_operator_map.items()}
 
-
-def tosa_type_name(builtin):
-    return next(k for k, v in vars(TosaOp).items() if v == builtin)
+tosa_operator_name_map = {v: k for k, v in vars(TosaOp).items()}
 
 
 # TODO will return UNKNOWN for the once that have not yet been defined in tosa_operator_map
-def optype_to_tosa_op_type(op_type):
+def optype_to_tosa_op_type(op_type: Op):
     if op_type in tosa_operator_inv_map:
-        return tosa_type_name(tosa_operator_inv_map[op_type][0])
+        return tosa_operator_name_map[tosa_operator_inv_map[op_type][0]]
     else:
         return TosaOp.UNKNOWN
diff --git a/ethosu/vela/vela.py b/ethosu/vela/vela.py
index 63cccc5..efe8edb 100644
--- a/ethosu/vela/vela.py
+++ b/ethosu/vela/vela.py
@@ -42,7 +42,7 @@
 from .tensor import Tensor
 from .tflite.Model import Model
 from .tflite_mapping import builtin_operator_map
-from .tflite_mapping import builtin_type_name
+from .tflite_mapping import builtin_operator_name_map
 from .tflite_model_semantic import TFLiteSemantic
 from .tflite_supported_operators import TFLiteSupportedOperators
 from .tosa_model_semantic import TosaSemantic
@@ -230,7 +230,7 @@
             raise ValueError
 
         op_constraint_links = []
-        op_list = sorted(((op, builtin_type_name(op)) for op in builtin_operator_map), key=lambda x: x[1])
+        op_list = sorted(((op, builtin_operator_name_map[op]) for op in builtin_operator_map), key=lambda x: x[1])
         for op, name in op_list:
             internal_op = builtin_operator_map[op][0]
             if internal_op in TFLiteSupportedOperators.supported_operators: