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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_chain(cur, chain, encoded_data=None):
 """Insert a chain into the cache. Args: cur (:class:`sqlite3.Cursor`):
 An sqlite3 cursor. This function is meant to be run within a :obj:`with` statement. chain (iterable):
 A collection of nodes. Chains in embedding act as one node. encoded_data (dict, optional):
 If a dictionary is provided, it will be populated with the serialized data. This is useful for preventing encoding the same information many times. Notes: This function assumes that the nodes in chain are index-labeled. """

    if encoded_data is None:
        encoded_data = {}

    if 'nodes' not in encoded_data:
        encoded_data['nodes'] = json.dumps(sorted(chain), separators=(',', ':'))
    if 'chain_length' not in encoded_data:
        encoded_data['chain_length'] = len(chain)

    insert = "INSERT OR IGNORE INTO chain(chain_length, nodes) VALUES (:chain_length, :nodes);"

    cur.execute(insert, encoded_data)