code: func Lookup(label string) (e encoding.Encoding, name string) {
  	label = strings.ToLower(strings.Trim(label, "\t\n\r\f "))
  	enc := encodings[label]
  	return enc.e, enc.name
  }
docs: // Lookup returns the encoding with the specified label, and its canonical
  // name. It returns nil and the empty string if label is not one of the
  // standard encodings for HTML. Matching is case-insensitive and ignores
  // leading and trailing whitespace.