src/sage/misc/lazy_import.pyx: Add comments

src/sage/misc/lazy_import.pyx

@@ -68,11 +68,17 @@ from warnings import warn
 import inspect
 from . import sageinspect
 
+
+# LazyImport.__repr__ uses try... except FeatureNotPresentError.
+# This is defined in sage.features, provided by the distribution sagemath-environment.
 try:
     from sage.features import FeatureNotPresentError
 except ImportError:
+    # If sage.features cannot be imported, then FeatureNotPresentError cannot
+    # be raised. In this case, use the empty tuple as the exception specification.
     FeatureNotPresentError = ()
 
+
 cdef inline obj(x):
     if type(x) is LazyImport:
         return (<LazyImport>x).get_object()
@@ -255,6 +261,7 @@ cdef class LazyImport():
             self._object = getattr(__import__(self._module, {}, {}, [self._name]), self._name)
         except ImportError as e:
             if self._feature:
+                # Avoid warnings from static type checkers by explicitly importing FeatureNotPresentError.
                 from sage.features import FeatureNotPresentError
                 raise FeatureNotPresentError(self._feature, reason=f'Importing {self._name} failed: {e}')
             raise