adding rss module from aikaterna to fix double post issue

rss/quiet_template.py

@@ -0,0 +1,31 @@
+from collections import ChainMap
+from string import Template
+
+
+class QuietTemplate(Template):
+    """
+    A subclass of string.Template that is less verbose on a missing key
+    https://github.com/python/cpython/blob/919f0bc8c904d3aa13eedb2dd1fe9c6b0555a591/Lib/string.py#L123
+    """
+
+    def quiet_safe_substitute(self, mapping={}, /, **kws):
+        if mapping is {}:
+            mapping = kws
+        elif kws:
+            mapping = ChainMap(kws, mapping)
+        # Helper function for .sub()
+        def convert(mo):
+            named = mo.group('named') or mo.group('braced')
+            if named is not None:
+                try:
+                    return str(mapping[named])
+                except KeyError:
+                    # return None instead of the tag name so that
+                    # invalid tags are not present in the feed output
+                    return None
+            if mo.group('escaped') is not None:
+                return self.delimiter
+            if mo.group('invalid') is not None:
+                return mo.group()
+            raise ValueError('Unrecognized named group in pattern', self.pattern)
+        return self.pattern.sub(convert, self.template)