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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 modify_config_file(updates):
    '''
    Update the config file with certain things
    '''
    cmd = '/bin/sed '
    for key in updates:
        cmd = cmd + '-e \'s/^#*{key}.*=.*$/{key}={value}/\' '.format(key=key, value=updates[key])
    cmd = cmd + constants.default_conf_file
    status = run_command_get_output(cmd)
    write_to_disk(constants.default_conf_file, content=status['output'])