adding firstfoundfile function

tldp/utils.py

@@ -24,6 +24,13 @@ def getLogger(**opts):
 
 logger = getLogger()
 
+def firstfoundfile(locations):
+    '''return the first existing file from a list of filenames (or None)'''
+    for option in locations:
+        if os.path.isfile(option):
+            return option
+    return None
+
 
 def stem_and_ext(name):
     '''return (stem, ext) for any relative or absolute filename'''