modules/gatsby/src/gatsby-node/create-webpack-config.js
function stringify(key, value) {
  if (value instanceof RegExp) {
    return value.toString();
  }
  if (value instanceof Function) {
    return '[function]';
  }
  return value;
}
function stringify(key, value) {
  if (value instanceof RegExp) {
    return value.toString();
  }
  if (value instanceof Function) {
    return '[function]';
  }
  return value;
}
function stringify ( key , value ) { if ( value instanceof RegExp ) { return value . toString ( ) ; } if ( value instanceof Function ) { return '[function]' ; } return value ; }
Makes JSON.stringify print regexps
Makes JSON . stringify print regexps