Identifies a known URL scheme
| Name | Description | 
|---|---|
| none | Indicates that no scheme is present | 
| unknown | Indicates the scheme is not a well-known scheme | 
| ftp | File Transfer Protocol (FTP) | 
| file | File URI Scheme | 
| http | The Hypertext Transfer Protocol URI Scheme | 
| https | The Secure Hypertext Transfer Protocol URI Scheme | 
| ws | The WebSocket URI Scheme | 
| wss | The Secure WebSocket URI Scheme | 
| Name | Description | 
|---|---|
| default_port | Return the default port for a known scheme | 
| string_to_scheme | Return the known scheme for a non-normalized string, if known | 
| to_string | Return the normalized string for a known scheme |