Fix&extend comments

oslex.py

@@ -4,7 +4,7 @@
 def is_posix() -> bool:
     """
     Returns whether the system running Python is POSIX compatible.
-    This is the condition for oslex.underyling being shlex.
+    This is the condition for oslex.underlying being shlex.
     This is also the condition for os.path being posixpath.
     """
     return 'posix' in sys.builtin_module_names
@@ -13,7 +13,7 @@ def is_posix() -> bool:
 def is_windows() -> bool:
     """
     Returns whether the system running Python is Windows based.
-    This is the condition for oslex.underyling being mslex.
+    This is the condition for oslex.underlying being mslex.
     This is also the condition for os.path being ntpath.
     """
 
@@ -31,7 +31,7 @@ def is_windows() -> bool:
     import shlex as underlying
 elif is_windows():
     # mslex has no type annotations -> we have to ignore the "import" error
-    # also, mypy does not understand conditioanl importing, so it thinks we are redefining the name -> we have to ignore the "no-redef" error
+    # also, mypy does not understand conditional importing, so it thinks we are redefining the name "underlying" -> we have to ignore the "no-redef" error
     import mslex as underlying  # type: ignore[import, no-redef]
 else:
     raise ImportError('no os specific module found')
@@ -61,7 +61,8 @@ def join(split_command: list[str]) -> str:
     The returned value is shell-escaped to protect against injection vulnerabilities (see quote()).
     This function is safe to use both for POSIX-compatible shells and for Windows's cmd.
     """
-    # shlex only has join() since python 3.8
+    # shlex only has join() since Python 3.8
     # mslex doesn't have it at all
-    # it's easier to just implement it without trying to import the functionality
+    # It's easier to just implement it without trying to import the functionality
+    # Implementation is the same as shlex.join(), see https://github.com/python/cpython/blob/3.8/Lib/shlex.py
     return ' '.join(quote(arg) for arg in split_command)