whole_func_string: function createLogger(conf, bitwise) {
    conf = conf || {};
    if(conf.json === undefined) conf.json = true;
    return new Logger(conf, bitwise);
  }
func_code_string: function createLogger(conf, bitwise) {
    conf = conf || {};
    if(conf.json === undefined) conf.json = true;
    return new Logger(conf, bitwise);
  }
func_documentation_string: Create a Logger and set json configuration
  to true if it has not been defined.
  
  Defined for bunyan compatibility.
  
  @param conf The logger configuration.
  @param bitwise A boolean indicating that log levels
  should use bitwise operators.