diff --git a/ansibleplaybookgrapher/__init__.py b/ansibleplaybookgrapher/__init__.py
index 86e6541d..ccd20efa 100644
--- a/ansibleplaybookgrapher/__init__.py
+++ b/ansibleplaybookgrapher/__init__.py
@@ -53,7 +53,8 @@ def parse(
         :param tags: Only add plays and tasks tagged with these values
         :param skip_tags: Only add plays and tasks whose tags do not match these values
         :param group_roles_by_name: Group roles by name instead of considering them as separate nodes with different IDs
-        :return:
+        :return: Tuple of the list of playbook nodes and the dictionary of the role usages: the key is the role and the
+        value is the set of plays that use the role.
         """
         playbook_nodes = []
         roles_usage: Dict[RoleNode, Set[PlayNode]] = {}
diff --git a/ansibleplaybookgrapher/renderer/__init__.py b/ansibleplaybookgrapher/renderer/__init__.py
index 4b5d7736..5f32ce9c 100644
--- a/ansibleplaybookgrapher/renderer/__init__.py
+++ b/ansibleplaybookgrapher/renderer/__init__.py
@@ -13,7 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 from abc import ABC, abstractmethod
-from typing import Dict, Optional, Set
+from typing import Dict, Optional, Set, List
 
 from ansible.utils.display import Display
 
@@ -44,7 +44,7 @@
 class Renderer(ABC):
     def __init__(
         self,
-        playbook_nodes: PlaybookNode,
+        playbook_nodes: List[PlaybookNode],
         roles_usage: Dict[RoleNode, Set[PlayNode]],
     ):
         self.playbook_nodes = playbook_nodes
@@ -73,7 +73,7 @@ def render(
 
 class PlaybookBuilder(ABC):
     """
-    This the base class to inherit from by the renderer to build a single Playbook in the target format.
+    This is the base class to inherit from by the renderer to build a single Playbook in the target format.
     It provides some methods that need to be implemented
     """
 
diff --git a/ansibleplaybookgrapher/renderer/graphviz/__init__.py b/ansibleplaybookgrapher/renderer/graphviz/__init__.py
index f238cfcf..831897cd 100644
--- a/ansibleplaybookgrapher/renderer/graphviz/__init__.py
+++ b/ansibleplaybookgrapher/renderer/graphviz/__init__.py
@@ -45,8 +45,7 @@ def __init__(
         playbook_nodes: List[PlaybookNode],
         roles_usage: Dict["RoleNode", Set[PlayNode]],
     ):
-        self.playbook_nodes = playbook_nodes
-        self.roles_usage = roles_usage
+        super().__init__(playbook_nodes, roles_usage)
 
     def render(
         self,
diff --git a/ansibleplaybookgrapher/renderer/mermaid.py b/ansibleplaybookgrapher/renderer/mermaid.py
index 002c36b5..fb208c87 100644
--- a/ansibleplaybookgrapher/renderer/mermaid.py
+++ b/ansibleplaybookgrapher/renderer/mermaid.py
@@ -12,6 +12,7 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 from pathlib import Path
 from typing import Dict, Set, List
 
@@ -23,9 +24,7 @@
 display = Display()
 
 # Default directive when rendering the graph.
-# More info at
-#   https://mermaid.js.org/config/directives.html
-#
+# More info at https://mermaid.js.org/config/directives.html
 DEFAULT_DIRECTIVE = '%%{ init: { "flowchart": { "curve": "bumpX" } } }%%'
 DEFAULT_ORIENTATION = "LR"  # Left to right
 
@@ -36,8 +35,7 @@ def __init__(
         playbook_nodes: List[PlaybookNode],
         roles_usage: Dict["RoleNode", Set[PlayNode]],
     ):
-        self.playbook_nodes = playbook_nodes
-        self.roles_usage = roles_usage
+        super().__init__(playbook_nodes, roles_usage)
 
     def render(
         self,
@@ -106,7 +104,7 @@ def render(
                 "The --view option is not supported yet by the mermaid renderer"
             )
 
-        return final_output_path_file
+        return str(final_output_path_file)
 
 
 class MermaidFlowChartPlaybookBuilder(PlaybookBuilder):