fix liniting issues and add type annotations

nominatim/server/falcon/server.py

@@ -7,8 +7,10 @@
 """
 Server implementation using the falcon webserver framework.
 """
+from typing import Type, Any
 from pathlib import Path
 
+import falcon
 import falcon.asgi
 
 from nominatim.api import NominatimAPIAsync
@@ -21,15 +23,22 @@ CONTENT_TYPE = {
 }
 
 class NominatimV1:
+    """ Implementation of V1 version of the Nominatim API.
+    """
 
-    def __init__(self, project_dir: Path):
+    def __init__(self, project_dir: Path) -> None:
         self.api = NominatimAPIAsync(project_dir)
         self.formatters = {}
 
         for rtype in (StatusResult, ):
             self.formatters[rtype] = formatting.create(rtype)
 
-    def parse_format(self, req, rtype, default):
+
+    def parse_format(self, req: falcon.asgi.Request, rtype: Type[Any], default: str) -> None:
+        """ Get and check the 'format' parameter and prepare the formatter.
+            `rtype` describes the expected return type and `default` the
+            format value to assume when no parameter is present.
+        """
         req.context.format = req.get_param('format', default=default)
         req.context.formatter = self.formatters[rtype]
 
@@ -39,12 +48,18 @@ class NominatimV1:
                             ', '.join(req.context.formatter.list_formats()))
 
 
-    def format_response(self, req, resp, result):
+    def format_response(self, req: falcon.asgi.Request, resp: falcon.asgi.Response,
+                        result: Any) -> None:
+        """ Render response into a string according to the formatter
+            set in `parse_format()`.
+        """
         resp.text = req.context.formatter.format(result, req.context.format)
         resp.content_type = CONTENT_TYPE.get(req.context.format, falcon.MEDIA_JSON)
 
 
-    async def on_get_status(self, req, resp):
+    async def on_get_status(self, req: falcon.asgi.Request, resp: falcon.asgi.Response) -> None:
+        """ Implementation of status endpoint.
+        """
         self.parse_format(req, StatusResult, 'text')
 
         result = await self.api.status()
@@ -53,6 +68,8 @@ class NominatimV1:
 
 
 def get_application(project_dir: Path) -> falcon.asgi.App:
+    """ Create a Nominatim falcon ASGI application.
+    """
     app = falcon.asgi.App()
 
     api = NominatimV1(project_dir)