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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def insert(self, key, value):
 """Inserts a key and value in the map if the map does not already contain the key. :type key: :class: '~opencensus.tags.tag_key.TagKey' :param key: a tag key to insert into the map :type value: :class: '~opencensus.tags.tag_value.TagValue' :param value: a tag value that is associated with the tag key and the value to insert into the tag map """

        if key in self.map:
            return

        try:
            tag_key = TagKey(key)
            tag_val = TagValue(value)
            self.map[tag_key] = tag_val
        except ValueError:
            raise