diff --git a/mathicsscript/bindkeys.py b/mathicsscript/bindkeys.py
index 755c521..5c82aeb 100644
--- a/mathicsscript/bindkeys.py
+++ b/mathicsscript/bindkeys.py
@@ -13,6 +13,11 @@
 #   You should have received a copy of the GNU General Public License
 #   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+"""
+Keyboard input binding routines for prompt_toolkit which are
+analogous to GNU Readlines' parse_and_bind().
+"""
+
 from typing import Callable
 from prompt_toolkit.enums import EditingMode
 from prompt_toolkit.key_binding import KeyBindings
@@ -136,7 +141,7 @@ def read_inputrc(read_init_file_fn: Callable, use_unicode: bool) -> None:
     """
     Read GNU Readline style inputrc
     """
-    # GNU Readling inputrc $include's paths are relative to itself,
+    # GNU Readline inputrc $include's paths are relative to itself,
     # so chdir to its directory before reading the file.
     parent_dir = pathlib.Path(__file__).parent.absolute()
     with parent_dir:
diff --git a/mathicsscript/completion.py b/mathicsscript/completion.py
index 6258d22..c70cc4a 100644
--- a/mathicsscript/completion.py
+++ b/mathicsscript/completion.py
@@ -83,7 +83,7 @@ def __init__(self, definitions):
 
         self.escape_sequences = aliased_characters.keys()
 
-    def _is_space_before_cursor(self, document, text_before_cursor: str) -> bool:
+    def _is_space_before_cursor(self, text_before_cursor: str) -> bool:
         """Space before or no text before cursor."""
         return text_before_cursor == "" or text_before_cursor[-1:].isspace()
 
@@ -135,9 +135,7 @@ def get_word_before_cursor_with_kind(
 
         text_before_cursor = document.text_before_cursor
 
-        if self._is_space_before_cursor(
-            document=document, text_before_cursor=text_before_cursor
-        ):
+        if self._is_space_before_cursor(text_before_cursor=text_before_cursor):
             return WordToken("", TokenKind.Null)
 
         start = (