def construct_mapping(self, node, deep=False):
mapping = super(ExtendedSafeConstructor, self).construct_mapping(<EOL>node, deep)<EOL>return {<EOL>(str(key) if isinstance(key, int) else key): mapping[key]<EOL>for key in mapping<EOL>}<EOL>
While yaml supports integer keys, these are not valid in
        json, and will break jsonschema. This method coerces all keys
        to strings.