add docstring

src/blop/agent.py

@@ -192,6 +192,8 @@ def sample(self, n: int = DEFAULT_MAX_SAMPLES, normalize: bool = False, method:
             How many points to sample.
         method : str
             How to sample the points. Must be one of 'quasi-random', 'random', or 'grid'.
+        normalize: bool
+            If True, sample the unit hypercube. If False, sample the parameter space of the agent.
         """
 
         active_dofs = self.dofs(active=True)

src/blop/objectives.py

@@ -334,10 +334,10 @@ def _test_obj(obj, active=None, fitness=None, constraint=None):
             if obj.active != active:
                 return False
         if fitness is not None:
-            if obj.target is None:
+            if fitness != (obj.target is not None):
                 return False
         if constraint is not None:
-            if obj.constraint is None:
+            if constraint != (obj.constraint is not None):
                 return False
         return True