diff --git a/notes/structure.md b/notes/structure.md
deleted file mode 100644
index 960892c..0000000
--- a/notes/structure.md
+++ /dev/null
@@ -1,30 +0,0 @@
-Upstream requirements are expressed as objects derived from UpstreamRequirement.
-
-They can either be:
-
- * extracted from the build system
- * extracted from errors in build logs
-
-The details of UpstreamRequirements are specific to the kind of requirement,
-and otherwise opaque to ognibuild.
-
-When building a package, we first make sure that all declared upstream
-requirements are met.
-
-Then we attempt to build.
-
-If any problems are found in the log, buildlog-consultant will report them.
-
-ognibuild can then invoke "fixers" to address Problems.
-
-Problems can be converted to UpstreamRequirements by UpstreamRequirementFixer
-
-Other Fixer can do things like e.g. upgrade configure.ac to a newer version.
-
-UpstreamRequirementFixer uses a UpstreamRequirementResolver object that
-can translate UpstreamRequirement objects into apt package names or
-e.g. cpan commands.
-
-ognibuild keeps finding problems, resolving them and rebuilding until it finds
-a problem it can not resolve or that it thinks it has already resolved
-(i.e. seen before).
diff --git a/ognibuild/resolver/apt.py b/ognibuild/resolver/apt.py
index 5fe42d8..df1adb2 100644
--- a/ognibuild/resolver/apt.py
+++ b/ognibuild/resolver/apt.py
@@ -22,7 +22,6 @@ from ..apt import AptManager
 from . import Resolver
 from ..requirements import (
     BinaryRequirement,
-    PythonPackageRequirement,
     )