index.js
function extname(ext) {
  var str = ext.charAt(0) === '.' ? ext.slice(1) : ext;
  if (str === 'yml') str = 'yaml';
  return str;
}
function extname(ext) {
  var str = ext.charAt(0) === '.' ? ext.slice(1) : ext;
  if (str === 'yml') str = 'yaml';
  return str;
}
function extname ( ext ) { var str = ext . charAt ( 0 ) === '.' ? ext . slice ( 1 ) : ext ; if ( str === 'yml' ) str = 'yaml' ; return str ; }
Get the extname without leading `.`
Get the extname without leading .