code: def set_connection(connection=defaults.sqlalchemy_connection_string_default):
      
      config_path = defaults.config_file_path
      config = RawConfigParser()
  
      if not os.path.exists(config_path):
          with open(config_path, 'w') as config_file:
              config['database'] = {'sqlalchemy_connection_string': connection}
              config.write(config_file)
              log.info('create configuration file {}'.format(config_path))
      else:
          config.read(config_path)
          config.set('database', 'sqlalchemy_connection_string', connection)
          with open(config_path, 'w') as configfile:
              config.write(configfile)
docs: Set the connection string for sqlalchemy and write it to the config file.
  
      .. code-block:: python
  
          import pyhgnc
          pyhgnc.set_connection('mysql+pymysql://{user}:{passwd}@{host}/{db}?charset={charset}')
  
  
      .. hint::
  
          valid connection strings
  
          - mysql+pymysql://user:passwd@localhost/database?charset=utf8
  
          - postgresql://scott:tiger@localhost/mydatabase
  
          - mssql+pyodbc://user:passwd@database
  
          - oracle://user:passwd@127.0.0.1:1521/database
  
          - Linux: sqlite:////absolute/path/to/database.db
  
          - Windows: sqlite:///C:\path\to\database.db
  
  
  
      :param str connection: sqlalchemy connection string