Fix lint and type errors in Python and Rust

Python:
- Fix mypy Optional[str] type error in parse_indented
- Fix ruff E712 comparison to True in experiment
- Fix ruff E402 import order in experiment

Rust:
- Remove redundant else block in escape_reference
- Add BuildHasher generic to format_indented for clippy
- Convert match to let-else pattern in parse_indented

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: konard

python/experiments/test_codec_simple.py

@@ -22,7 +22,7 @@
     print(f"Encoded: {encoded}")
     decoded = decode(encoded)
     print(f"Decoded: {decoded}")
-    print(f"Match: {decoded == True}")
+    print(f"Match: {decoded is True}")
 except Exception as e:
     print(f"Error: {e}")
     import traceback

python/experiments/test_mutual_dicts.py

@@ -1,6 +1,7 @@
 """Test mutual reference dicts."""
 
 from link_notation_objects_codec import encode
+from links_notation import Parser
 
 dict1 = {"name": "dict1"}
 dict2 = {"name": "dict2"}
@@ -11,7 +12,6 @@
 print(f"Encoded: {encoded}")
 
 # Parse it to see the structure
-from links_notation import Parser
 
 parser = Parser()
 links = parser.parse(encoded)

python/src/link_notation_objects_codec/format.py

@@ -202,7 +202,11 @@ def parse_indented(text: str) -> Tuple[str, Dict[str, Any]]:
             key.startswith('"') and key.endswith('"')
         ):
             key = key[1:-1]
-        unescaped_key = unescape_reference(key)
+        unescaped_key_result = unescape_reference(key)
+        # unescape_reference only returns None if input is None, but key is always str here
+        unescaped_key: str = (
+            unescaped_key_result if unescaped_key_result is not None else key
+        )
 
         # Parse value (remove surrounding quotes and unescape doubled quotes)
         if value.startswith('"') and value.endswith('"'):

rust/src/lib.rs

@@ -963,11 +963,10 @@ pub mod format {
                 // Use double quotes, escape internal double quotes by doubling
                 let escaped = value.replace('"', "\"\"");
                 return format!("\"{}\"", escaped);
-            } else {
-                // Use single quotes, escape internal single quotes by doubling
-                let escaped = value.replace('\'', "''");
-                return format!("'{}'", escaped);
             }
+            // Use single quotes, escape internal single quotes by doubling
+            let escaped = value.replace('\'', "''");
+            return format!("'{}'", escaped);
         }
 
         // Just spaces or other special characters, use single quotes by default
@@ -1031,9 +1030,9 @@ pub mod format {
     /// let result = format_indented("my-uuid", &obj, "  ").unwrap();
     /// assert!(result.starts_with("my-uuid\n"));
     /// ```
-    pub fn format_indented(
+    pub fn format_indented<S: ::std::hash::BuildHasher>(
         id: &str,
-        obj: &HashMap<String, String>,
+        obj: &HashMap<String, String, S>,
         indent: &str,
     ) -> Result<String, FormatError> {
         if id.is_empty() {
@@ -1139,9 +1138,8 @@ pub mod format {
             }
 
             // Find the first space that separates key from value
-            let space_index = match trimmed.find(' ') {
-                Some(i) => i,
-                None => continue, // No value, skip this line
+            let Some(space_index) = trimmed.find(' ') else {
+                continue; // No value, skip this line
             };
 
             let key = &trimmed[..space_index];