  |
Uniform Resource Identifier (URI): 一般的構文
https://triple-underscore.github.io/rfc-others/RFC3986-ja.html#section-3
URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ] hier-part = "//" authority path-abempty / path-absolute / path-rootless / path-empty
: は scheme と hier-part を区切るために必要
4
