diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..6c2ff60
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,5 @@
+{
+    "githubPullRequests.ignoredPullRequestBranches": [
+        "master"
+    ]
+}
\ No newline at end of file
diff --git a/doc/b.png b/doc/b.png
new file mode 100644
index 0000000..0c1db84
Binary files /dev/null and b/doc/b.png differ