[mod] addition of various type hints / tbc

- pyright configuration [1]_
- stub files: types-lxml [2]_
- addition of various type hints
- enable use of new type system features on older Python versions [3]_
- ``.tool-versions`` - set python to lowest version we support (3.10.18) [4]_:
  Older versions typically lack some typing features found in newer Python
  versions.  Therefore, for local type checking (before commit), it is necessary
  to use the older Python interpreter.

.. [1] https://docs.basedpyright.com/v1.20.0/configuration/config-files/
.. [2] https://pypi.org/project/types-lxml/
.. [3] https://typing-extensions.readthedocs.io/en/latest/#
.. [4] https://mise.jdx.dev/configuration.html#tool-versions

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Format: reST

searx/openmetrics.py

@@ -1,27 +1,45 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """Module providing support for displaying data in OpenMetrics format"""
 
+import typing as t
+
+OMFTypeHintType = t.Literal["counter", "gauge", "histogram", "summary"]
+OMFDataInfoType = list[dict[str, str]]
+OMFDataType = list[t.Any]
+
 
 class OpenMetricsFamily:  # pylint: disable=too-few-public-methods
     """A family of metrics.
-    The key parameter is the metric name that should be used (snake case).
-    The type_hint parameter must be one of 'counter', 'gauge', 'histogram', 'summary'.
-    The help_hint parameter is a short string explaining the metric.
-    The data_info parameter is a dictionary of descriptionary parameters for the data point (e.g. request method/path).
-    The data parameter is a flat list of the actual data in shape of a primitive type.
 
-    See https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md for more information.
+    - The ``key`` parameter is the metric name that should be used (snake case).
+    - The ``type_hint`` parameter must be one of ``counter``, ``gauge``,
+      ``histogram``, ``summary``.
+    - The ``help_hint`` parameter is a short string explaining the metric.
+    - The data_info parameter is a dictionary of descriptionary parameters for
+      the data point (e.g. request method/path).
+
+    - The data parameter is a flat list of the actual data in shape of a
+      primitive type.
+
+    See `OpenMetrics specification`_ for more information.
+
+    .. _OpenMetrics specification:
+       https://github.com/prometheus/OpenMetrics/blob/main/specification/OpenMetrics.txt
+
     """
 
-    def __init__(self, key: str, type_hint: str, help_hint: str, data_info: list, data: list):
-        self.key = key
-        self.type_hint = type_hint
-        self.help_hint = help_hint
-        self.data_info = data_info
-        self.data = data
+    def __init__(
+        self, key: str, type_hint: OMFTypeHintType, help_hint: str, data_info: OMFDataInfoType, data: list[t.Any]
+    ):
+        self.key: str = key
+        self.type_hint: OMFTypeHintType = type_hint
+        self.help_hint: str = help_hint
+        self.data_info: OMFDataInfoType = data_info
+        self.data: OMFDataType = data
 
     def __str__(self):
-        text_representation = f"""# HELP {self.key} {self.help_hint}
+        text_representation = f"""\
+# HELP {self.key} {self.help_hint}
 # TYPE {self.key} {self.type_hint}
 """
 
@@ -29,7 +47,7 @@ class OpenMetricsFamily:  # pylint: disable=too-few-public-methods
             if not data_info_dict or not self.data[i]:
                 continue
 
-            info_representation = ','.join([f"{key}=\"{value}\"" for (key, value) in data_info_dict.items()])
-            text_representation += f"{self.key}{{{info_representation}}} {self.data[i]}\n"
+            info_representation = ','.join([f'{key}="{value}"' for (key, value) in data_info_dict.items()])
+            text_representation += f'{self.key}{{{info_representation}}} {self.data[i]}\n'
 
         return text_representation