diff --git a/src/mojxml/parse.py b/src/mojxml/parse.py
index d6f3c8f..aea59f3 100644
--- a/src/mojxml/parse.py
+++ b/src/mojxml/parse.py
@@ -186,7 +186,7 @@ def _parse_features(
 
 
 def parse_raw(content: bytes, options: ParseOptions) -> List[Feature]:
-    """TODO:"""
+    """Parse raw XML content and get list of features."""
     doc = et.fromstring(content, None)
 
     # 基本情報を取得
diff --git a/src/mojxml/process/__init__.py b/src/mojxml/process/__init__.py
index 8dd11d8..b4eed92 100644
--- a/src/mojxml/process/__init__.py
+++ b/src/mojxml/process/__init__.py
@@ -22,7 +22,6 @@ def _write_by_fiona(
     dst_path: Path,
     driver: Optional[str] = None,
 ) -> Iterable[Tuple[int, int]]:  # (num_files, num_features)
-    """WIP"""
     assert fiona, "fiona is not installed"
 
     with fiona.open(
@@ -47,7 +46,7 @@ def files_to_ogr_file(
     executor: BaseExecutor,
     driver: Optional[str] = None,
 ) -> None:
-    """WIP"""
+    """Generate OGR file from given XML/ZIP files."""
     features_iter = executor.iter_process(iter_content_xmls(src_paths))
 
     num_files = 0
@@ -67,7 +66,7 @@ def files_to_ogr_file(
 def files_to_feature_iter(
     src_paths: List[Path], executor: BaseExecutor
 ) -> Iterable[Feature]:
-    """WIP"""
+    """Iterate features from given XML/ZIP files."""
     features_iter = executor.iter_process(iter_content_xmls(src_paths))
     for features in features_iter:
         for feature in features:
diff --git a/src/mojxml/process/executor.py b/src/mojxml/process/executor.py
index 641892c..9e1df12 100644
--- a/src/mojxml/process/executor.py
+++ b/src/mojxml/process/executor.py
@@ -12,7 +12,7 @@ class BaseExecutor(metaclass=ABCMeta):
     """Executor for processing files"""
 
     def __init__(self, options: ParseOptions):
-        """TODO"""
+        """Initialize"""
         self.options = options
 
     @abstractmethod
@@ -20,23 +20,23 @@ def iter_process(
         self,
         src_iter: Iterable[bytes],
     ) -> Iterable[List[Feature]]:
-        """TODO"""
+        """Convert XMLs to OGR features"""
 
 
 class WorkerPoolExecutor(BaseExecutor, metaclass=ABCMeta):
-    """TODO"""
+    """Executor implemeted with worker pool"""
 
     @abstractmethod
-    def get_executor(self, max_workers: int) -> concurrent.futures.Executor:
-        """TODO"""
+    def _get_executor(self, max_workers: int) -> concurrent.futures.Executor:
+        ...
 
     def iter_process(
         self,
         src_iter: Iterable[bytes],
     ) -> Iterable[List[Feature]]:
-        """TODO"""
+        """Convert XMLs to OGR features"""
         max_workers = os.cpu_count() or 1
-        with self.get_executor(max_workers=max_workers) as executor:
+        with self._get_executor(max_workers=max_workers) as executor:
             futs = []
             for src in src_iter:
                 fut = executor.submit(parse_raw, src, self.options)
@@ -60,8 +60,7 @@ def iter_process(
 class ProcessPoolExecutor(WorkerPoolExecutor):
     """Process paralelly with ProcessPoolExecutor"""
 
-    def get_executor(self, max_workers: int) -> concurrent.futures.Executor:
-        """TODO"""
+    def _get_executor(self, max_workers: int) -> concurrent.futures.Executor:
         max_workers = os.cpu_count() or 1
         return concurrent.futures.ProcessPoolExecutor(max_workers=max_workers)
 
@@ -69,20 +68,16 @@ def get_executor(self, max_workers: int) -> concurrent.futures.Executor:
 class ThreadPoolExecutor(WorkerPoolExecutor):
     """Process paralelly with ThreadPoolExecutor"""
 
-    def get_executor(self, max_workers: int) -> concurrent.futures.Executor:
-        """TODO"""
+    def _get_executor(self, max_workers: int) -> concurrent.futures.Executor:
         max_workers = (os.cpu_count() or 1) * 2
         return concurrent.futures.ThreadPoolExecutor(max_workers=max_workers)
 
 
 class SingleThreadExecutor(BaseExecutor):
-    """Process files with normal iterator"""
+    """Process files with single-thread (normal) iterator"""
 
-    def iter_process(
-        self,
-        src_iter: Iterable[bytes],
-    ) -> Iterable[List[Feature]]:
-        """TODO"""
+    def iter_process(self, src_iter: Iterable[bytes]) -> Iterable[List[Feature]]:
+        """Convert XMLs to OGR features"""
         for src in src_iter:
             yield parse_raw(src, options=self.options)
 
diff --git a/src/mojxml/reader.py b/src/mojxml/reader.py
index b4810a7..a895fe0 100644
--- a/src/mojxml/reader.py
+++ b/src/mojxml/reader.py
@@ -6,7 +6,7 @@
 
 
 def iter_content_xmls(src_paths: List[Path]) -> Iterable[bytes]:
-    """WIP"""
+    """Iterate XML contents from given zips and xmls"""
     for src_path in src_paths:
         src_path = Path(src_path)
         if src_path.suffix == ".xml":
@@ -23,7 +23,7 @@ class MojXMLZipFile(ZipFile):
     """法務省登記所備付地図データの多段zip圧縮されたアーカイブを扱う"""
 
     def iter_xml_contents(self):
-        """TODO"""
+        """Iterate XML contents from given zips"""
         for name in self.namelist():
             if name.endswith(".zip"):
                 yield self._extract_xml_content(name[:-4])
@@ -31,7 +31,6 @@ def iter_xml_contents(self):
                 yield self.open(name).read()
 
     def _extract_xml_content(self, internal_name: str) -> bytes:
-        """TODO"""
         with self.open(internal_name + ".zip") as f:
             with ZipFile(f) as zf:
                 xml_content = zf.open(internal_name + ".xml").read()