[data_lang] Add pretty printing benchmark

It takes much longer to print than to parse.  See snippet in shell
script.

data_lang/pretty-benchmark.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+#
+# Usage:
+#   data_lang/pretty-benchmark.sh <function name>
+
+set -o nounset
+set -o pipefail
+set -o errexit
+
+# Only show real time
+TIMEFORMAT='%R'
+# User time is also interesting
+# TIMEFORMAT='%U'
+
+# It takes much longer to print than to parse.
+#
+# Output example:
+#
+# benchmarks/testdata/configure-coreutils - parsing only, then parsing and printing
+# AST not printed.
+# 0.129
+# 
+# 108811544  # <-- This is 109 MB of output text!
+# 3.679
+
+compare() {
+  local osh=_bin/cxx-opt/osh
+  ninja $osh
+
+  for file in benchmarks/testdata/*; do
+    echo ---
+    echo "$file - parsing only, then parsing and printing"
+
+    # Don't print at all.  configure-coreutils is 136 ms.
+    time $osh --ast-format none --tool syntax-tree $file
+    echo
+
+    # Print the whole thing
+    time $osh --ast-format text --tool syntax-tree $file | wc --bytes
+    echo
+
+  done
+}
+
+"$@"

data_lang/pretty_test.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python2
+"""
+pretty_test.py
+"""
+
+import unittest
+
+from data_lang import pretty  # module under test
+
+
+class PrettyTest(unittest.TestCase):
+
+    def testFoo(self):
+        print(pretty)
+
+
+if __name__ == '__main__':
+    unittest.main()

tools/fmt_test.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python2
+"""
+fmt_test.py
+"""
+
+import unittest
+
+from tools import fmt # module under test
+
+
+class FmtTest(unittest.TestCase):
+
+    def testFoo(self):
+        print(fmt)
+
+
+if __name__ == '__main__':
+    unittest.main()