epsgLookup = async function (code) {
  const response = await fetch(`https://epsg.io/${code}.proj4`);
  if (!response.ok) {
    throw new Error(`Unexpected response from epsg.io: ${response.status}`);
  }
  return response.text();
}
@param {number} code The EPSG code.
@return {Promise<string>} The proj4 definition.