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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_feasible_configurations(cur, feasible_configurations, encoded_data=None):
 """Insert a group of feasible configurations into the cache. Args: cur (:class:`sqlite3.Cursor`):
 An sqlite3 cursor. This function is meant to be run within a :obj:`with` statement. feasible_configurations (dict[tuple[int]):
 The set of feasible configurations. Each key should be a tuple of variable assignments. The values are the relative energies. 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. Examples: """

    if encoded_data is None:
        encoded_data = {}

    if 'num_variables' not in encoded_data:
        encoded_data['num_variables'] = len(next(iter(feasible_configurations)))
    if 'num_feasible_configurations' not in encoded_data:
        encoded_data['num_feasible_configurations'] = len(feasible_configurations)
    if 'feasible_configurations' not in encoded_data or 'energies' not in encoded_data:
        encoded = {_serialize_config(config): en for config, en in feasible_configurations.items()}

        configs, energies = zip(*sorted(encoded.items()))
        encoded_data['feasible_configurations'] = json.dumps(configs, separators=(',', ':'))
        encoded_data['energies'] = json.dumps(energies, separators=(',', ':'))

    insert = """
            INSERT OR IGNORE INTO feasible_configurations(
                num_variables,
                num_feasible_configurations,
                feasible_configurations,
                energies)
            VALUES (
                :num_variables,
                :num_feasible_configurations,
                :feasible_configurations,
                :energies);
            """

    cur.execute(insert, encoded_data)