lib/manager/pipenv/update.js
function replaceAt(content, index, oldString, newString) {
  logger.debug(`Replacing ${oldString} with ${newString} at index ${index}`);
  return (
    content.substr(0, index) +
    newString +
    content.substr(index + oldString.length)
  );
}
function replaceAt(content, index, oldString, newString) {
  logger.debug(`Replacing ${oldString} with ${newString} at index ${index}`);
  return (
    content.substr(0, index) +
    newString +
    content.substr(index + oldString.length)
  );
}
function replaceAt ( content , index , oldString , newString ) { logger . debug ( ` ${ oldString } ${ newString } ${ index } ` ) ; return ( content . substr ( 0 , index ) + newString + content . substr ( index + oldString . length ) ) ; }
Replace oldString with newString at location index of content
Replace oldString with newString at location index of content