<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def insert(self, key, value, ttl=0, format=None, persist_to=0, replicate_to=0):
 """Store an object in Couchbase unless it already exists. Follows the same conventions as :meth:`upsert` but the value is stored only if it does not exist already. Conversely, the value is not stored if the key already exists. Notably missing from this method is the `cas` parameter, this is because `insert` will only succeed if a key does not already exist on the server (and thus can have no CAS) :raise: :exc:`.KeyExistsError` if the key already exists .. seealso:: :meth:`upsert`, :meth:`insert_multi` """

        return _Base.insert(self, key, value, ttl=ttl, format=format,
                            persist_to=persist_to, replicate_to=replicate_to)