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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 create_default_config(self):
 """ Create default configuration if config file does not exist """

        # make config directory with the minimal possible permission
        self._config_file.parent.mkdir(mode=0o700, exist_ok=True)
        self["network.kovan"]   = {"default_eth_rpc_endpoint": "https://kovan.infura.io",   "default_gas_price" : "medium"}
        self["network.mainnet"] = {"default_eth_rpc_endpoint": "https://mainnet.infura.io", "default_gas_price" : "medium"}
        self["network.ropsten"] = {"default_eth_rpc_endpoint": "https://ropsten.infura.io", "default_gas_price" : "medium"}
        self["network.rinkeby"] = {"default_eth_rpc_endpoint": "https://rinkeby.infura.io", "default_gas_price" : "medium"}
        self["ipfs"] = {"default_ipfs_endpoint": "http://ipfs.singularitynet.io:80"}
        self["session"] = {
        "network": "kovan" }
        self._persist()
        print("We've created configuration file with default values in: %s\n"%str(self._config_file))