diff --git a/tools.py b/tools.py
new file mode 100644
index 0000000..ccccec2
--- /dev/null
+++ b/tools.py
@@ -0,0 +1,81 @@
+
+import subprocess
+import logging
+import yaml
+import markdown
+
+# setup logger for this module
+logger = logging.getLogger(__name__)
+
+# ---------------------------------------------------------------------------
+# load data from yaml file
+# ---------------------------------------------------------------------------
+def load_yaml(filename, default=None):
+    try:
+        f = open(filename, 'r', encoding='utf-8')
+    except IOError:
+        logger.error('Can\'t open file "{}"'.format(filename))
+        return default
+    else:
+        with f:
+            try:
+                return yaml.load(f)
+            except yaml.YAMLError as e:
+                mark = e.problem_mark
+                logger.error('In YAML file "{0}" near line {1}, column {2}.'.format(filename, mark.line, mark.column+1))
+                return default
+
+# ---------------------------------------------------------------------------
+# Runs a script and returns its stdout parsed as yaml, or None on error.
+# Note: requires python 3.5+
+# ---------------------------------------------------------------------------
+def run_script(script, stdin='', timeout=5):
+    try:
+        p = subprocess.run([script],
+            input=stdin,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            universal_newlines=True,
+            timeout=timeout,
+            )
+    except FileNotFoundError:
+        logger.error('Script not found: "{0}".'.format(script))
+    except PermissionError:
+        logger.error('Script "{0}" not executable (wrong permissions?).'.format(script))
+    except subprocess.TimeoutExpired:
+        logger.error('Timeout {0}s exceeded while running script "{1}"'.format(timeout, script))
+    else:
+        if p.returncode != 0:
+            logger.error('Script "{0}" returned error code {1}.'.format(script, p.returncode))
+        else:
+            try:
+                output = yaml.load(p.stdout)
+            except:
+                logger.error('Error parsing yaml output of script "{0}"'.format(script))
+            else:
+                return output
+
+def md_to_html(text, ref=None, files={}):
+    if ref is not None:
+        # given q['ref'] and q['files'] replaces references to files by a
+        # GET to /file?ref=???;name=???
+        for k in files:
+            text = text.replace(k, '/file?ref={};name={}'.format(ref, k))
+    return markdown.markdown(text, extensions=[
+        'markdown.extensions.tables',
+        'markdown.extensions.fenced_code',
+        'markdown.extensions.codehilite',
+        'markdown.extensions.def_list',
+        'markdown.extensions.sane_lists'
+    ])
+
+def md_to_html_review(text, q):
+    for k,f in q['files'].items():
+        text = text.replace(k, '/absfile?name={}'.format(q['files'][k]))
+    return markdown.markdown(text, extensions=[
+        'markdown.extensions.tables',
+        'markdown.extensions.fenced_code',
+        'markdown.extensions.codehilite',
+        'markdown.extensions.def_list',
+        'markdown.extensions.sane_lists'
+    ])
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