Add query to limit how many links we sample

Util/sample_links.py

@@ -47,14 +47,20 @@ def prompt_user_bool(prompt_msg, default=None, options_map=None):
         'palantir_plottable',
         'tensorflow_tensorflow',  # Dev set end
     ]
+    first_n = input('How many links should we sample?')
     hits = dict()
     for project in projects:
         hits[project] = list()
         with open((location_format[:-5] + '_truth.json') % project) as f:
             truth = jsonpickle.decode(f.read())
         issues = random.sample(list(truth.keys()), 100)
 
-        for issue in issues:
+        if first_n == 'all':
+            first_n_actual = len(issues)
+        else:
+            first_n_actual = min(int(first_n), len(issues))
+
+        for issue in issues[:first_n_actual]:
             issue_id = int(issue[1:])
             wb.open(url_format % (project.replace('_', '/'), issue_id))
             for other in truth[issue]: