next try

nifty6/linearization.py

@@ -19,7 +19,6 @@ import numpy as np
 
 from .sugar import makeOp
 from .operators.operator import Operator
-from .operators.sandwich_operator import SandwichOperator
 
 
 class Linearization(Operator):
@@ -66,7 +65,10 @@ class Linearization(Operator):
         return self.make_var(self._val, self._want_metric)
 
     def prepend_jac(self, jac):
-        metric = None if self._metric is None else SandwichOperator.make(jac, self._metric)
+        if self._metric is None:
+            return self.new(self._val, self._jac @ jac)
+        from .operators.sandwich_operator import SandwichOperator
+        metric = SandwichOperator.make(jac, self._metric)
         return self.new(self._val, self._jac @ jac, metric)
 
     @property