Include the python_gut tool

gut.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2015-2016 Andrew Hamilton. All rights reserved.
+# Licensed under the Artistic License 2.0.
+
+import re
+import sys
+
+
+USAGE = """Usage: gut.py <python file>
+
+# gut.py test.py"""
+
+
+INDENT_SIZE = 4
+TAB_SIZE = 4
+
+
+def indentation_of_line(line):
+    indentation = 0
+    for character in line:
+        if character == " ":
+            indentation += 1
+        elif character == "\t":
+            indentation += TAB_SIZE
+        elif character == "\n":
+            return None
+        else:  # Is a non-whitespace character.
+            return indentation
+
+
+def is_start_line_of_signature(line):
+    return re.match("^\s*def\s", line) is not None
+
+
+def is_end_line_of_signature(line):
+    return (re.match(".*\):\s*\n$", line) is not None or
+            re.match(".*\):\s*#.*\n$", line) is not None)
+
+
+def gut_module(module_contents):
+    SIGNATURE, BODY, TOP_LEVEL = 1, 2, 3
+    state = TOP_LEVEL
+    body_depth = 0
+    result = []
+    for line in module_contents.splitlines(keepends=True):
+        indent = indentation_of_line(line)
+        if state == BODY and indent is not None and \
+           indent < body_depth:
+            state = TOP_LEVEL
+            result.append("\n")
+        if state == TOP_LEVEL and is_start_line_of_signature(line):
+            state = SIGNATURE
+            body_depth = indent + INDENT_SIZE
+        if state == SIGNATURE and is_end_line_of_signature(line):
+            result.append(line)
+            state = BODY
+        elif state != BODY:
+            result.append(line)
+    return "".join(result)
+
+
+def main(module_path):
+    with open(module_path) as module_file:
+        print(gut_module(module_file.read()))
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        print(USAGE)
+        sys.exit(-1)
+    main(sys.argv[1])