diff --git a/bin/sarif-to-dot b/bin/sarif-to-dot
index 6b1b528..62865f0 100755
--- a/bin/sarif-to-dot
+++ b/bin/sarif-to-dot
@@ -15,7 +15,8 @@ context = S.Context(
         "string" : "String",
         "int" : "Int",
         "bool" : "Bool"
-    }) 
+    }
+) 
 
 parser = argparse.ArgumentParser(description='Produce a summary of signatures found in the sarif file.')
 parser.add_argument('file', metavar='sarif-file', type=str, help='input file, - for stdin')
@@ -65,7 +66,7 @@ if args.dot_output:
 elif args.typedef_signatures:
     S._signature(args, sarif_struct, context)
     struct_graph = [(typedef, sig) for sig,typedef in context.sig_to_typedef.items()]
-    pprint(struct_graph, sys.stdout, indent=2)
+    pprint(struct_graph, sys.stdout, indent=4)
 
 else:
-    pprint(S._signature(args, sarif_struct, context), sys.stdout, indent=2)
+    pprint(S._signature(args, sarif_struct, context), sys.stdout, indent=4)
diff --git a/notes/sarif-structure-from-sarif-to-dot-v-0b13a29.pdf b/notes/sarif-structure-from-sarif-to-dot-v-0b13a29.pdf
deleted file mode 100644
index 38df544..0000000
Binary files a/notes/sarif-structure-from-sarif-to-dot-v-0b13a29.pdf and /dev/null differ
diff --git a/notes/sarif-structure-from-sarif-to-dot.pdf b/notes/sarif-structure-from-sarif-to-dot.pdf
new file mode 100644
index 0000000..171e862
Binary files /dev/null and b/notes/sarif-structure-from-sarif-to-dot.pdf differ
diff --git a/sarif_cli/signature.py b/sarif_cli/signature.py
index a12fd98..59f9a27 100644
--- a/sarif_cli/signature.py
+++ b/sarif_cli/signature.py
@@ -30,16 +30,15 @@ import zlib
 #
 @dataclass
 class Context:
-    sig_to_typedef: dict        # signature to typedef name map
+    sig_to_typedef: dict                     # signature -> typedef name map
 
 def shorthash(signature):
     return zlib.adler32(str(signature).encode('utf-8')) % 10000
 
-
 #
 # Signature formation
 #
-def _signature_dict(args, elem, context):
+def _signature_dict(args, elem, context: Context):
     """ Assemble and return the signature for a dictionary.
     """
     # Collect signatures
@@ -55,8 +54,10 @@ def _signature_dict(args, elem, context):
         # Give every unique struct a name and use a reference to it as value.
         if signature not in context.sig_to_typedef:
             context.sig_to_typedef[signature] = "Struct%04d" % shorthash(signature)
-        signature = context.sig_to_typedef[signature]
-    return signature
+        typedef = context.sig_to_typedef[signature]
+        return typedef
+    else:
+        return signature
 
 def _signature_list(args, elem, context):
     """ Assemble and return the signature for a Python list.
@@ -79,8 +80,10 @@ def _signature_list(args, elem, context):
         # Give every unique array a name and use a reference to it as value.
         if signature not in context.sig_to_typedef:
             context.sig_to_typedef[signature] = "Array%04d" % shorthash(signature)
-        signature = context.sig_to_typedef[signature]
-    return signature
+        typedef = context.sig_to_typedef[signature]
+        return typedef
+    else:
+        return signature
 
 def _signature(args, elem, context):
     """ Assemble and return the signature for a list/dict/value structure.