From `example_test.go` (note that in your code, you would import "github.com/PuerkitoBio/purell", and would prefix references to its methods and constants with "purell."):
```go
package purell
import (
"fmt"
"net/url"
)
func ExampleNormalizeURLString() {
if normalized, err := NormalizeURLString("hTTp://someWEBsite.com:80/Amazing%3f/url/",
As seen in the examples above, purell offers three methods, `NormalizeURLString(string, NormalizationFlags) (string, error)`, `MustNormalizeURLString(string, NormalizationFlags) (string)` and `NormalizeURL(*url.URL, NormalizationFlags) (string)`. They all normalize the provided URL based on the specified flags. Here are the available flags:
```go
const (
// Safe normalizations
FlagLowercaseScheme NormalizationFlags = 1 <<iota//HTTP://host-> http://host, applied by default in Go1.1
For convenience, the set of flags `FlagsSafe`, `FlagsUsuallySafe[Greedy|NonGreedy]`, `FlagsUnsafe[Greedy|NonGreedy]` and `FlagsAll[Greedy|NonGreedy]` are provided for the similarly grouped normalizations on [wikipedia's URL normalization page][wiki]. You can add (using the bitwise OR `|` operator) or remove (using the bitwise AND NOT `&^` operator) individual flags from the sets if required, to build your own custom set.
The [full godoc reference is available on gopkgdoc][godoc].
Some things to note:
*`FlagDecodeUnnecessaryEscapes`, `FlagEncodeNecessaryEscapes`, `FlagUppercaseEscapes` and `FlagRemoveEmptyQuerySeparator` are always implicitly set, because internally, the URL string is parsed as an URL object, which automatically decodes unnecessary escapes, uppercases and encodes necessary ones, and removes empty query separators (an unnecessary `?` at the end of the url). So this operation cannot **not** be done. For this reason, `FlagRemoveEmptyQuerySeparator` (as well as the other three) has been included in the `FlagsSafe` convenience set, instead of `FlagsUnsafe`, where Wikipedia puts it.
* The `FlagDecodeUnnecessaryEscapes` decodes the following escapes (*from -> to*):
- %24 -> $
- %26 -> &
- %2B-%3B -> +,-./0123456789:;
- %3D -> =
- %40-%5A -> @ABCDEFGHIJKLMNOPQRSTUVWXYZ
- %5F -> _
- %61-%7A -> abcdefghijklmnopqrstuvwxyz
- %7E -> ~
* When the `NormalizeURL` function is used (passing an URL object), this source URL object is modified (that is, after the call, the URL object will be modified to reflect the normalization).
* The *replace IP with domain name* normalization (`http://208.77.188.166/ → http://www.example.com/`) is obviously not possible for a library without making some network requests. This is not implemented in purell.
* The *remove unused query string parameters* and *remove default query parameters* are also not implemented, since this is a very case-specific normalization, and it is quite trivial to do with an URL object.
### Safe vs Usually Safe vs Unsafe
Purell allows you to control the level of risk you take while normalizing an URL. You can aggressively normalize, play it totally safe, or anything in between.
* Add a class/default instance to allow specifying custom directory index names? At the moment, removing directory index removes `(^|/)((?:default|index)\.\w{1,4})$`.
