Add get_linter

gitlint

@@ -12,17 +12,26 @@ linters = {
 }
 
 
-def lint(filename, fail_on_keyerror=False):
+class NoLinterFound(Exception):
+    pass
+
+
+def get_linter(filename):
     try:
         _, extension = filename.rsplit('.', 1)
-    except ValueError:
-        return True
+        linter_args = linters[extension]
+    except (KeyError, ValueError):
+        raise NoLinterFound
 
+    return linter_args
+
+
+def lint(filename, require_linter=False):
     try:
-        linter_args = linters[extension]
-    except KeyError:
+        linter_args = get_linter(filename)
+    except NoLinterFound:
         print('Not linter found for', filename, file=sys.stderr)
-        return not fail_on_keyerror
+        return not require_linter
 
     print(filename)
     git_args = ('/usr/bin/git', 'show', shlex.quote(':%s' % filename))