Simplify nested iteration in window attached_pane method

Author: otherJL0

libtmux/common.py

@@ -349,7 +349,7 @@ def by(val) -> bool:
         target_children = list(filter(by, self.children))
         if first:
             return target_children[0]
-        return return target_children
+        return target_children
 
     def get_by_id(self, id):
         """

libtmux/window.py

@@ -502,10 +502,9 @@ def attached_pane(self) -> t.Optional[Pane]:
         :class:`Pane`
         """
         for pane in self._panes:
-            if "pane_active" in pane:
-                # for now pane_active is a unicode
-                if pane.get("pane_active") == "1":
-                    return Pane(window=self, **pane)
+            # for now pane_active is a unicode
+            if "pane_active" in pane and pane.get("pane_active") == "1":
+                return Pane(window=self, **pane)
 
     def _list_panes(self) -> t.List[PaneDict]:
         panes = self.server._update_panes()._panes