join function
Joins the given path parts into a single path using the current platform's separator. Example:
p.join('path', 'to', 'foo'); // -> 'path/to/foo'
If any part ends in a path separator, then a redundant separator will not be added:
p.join('path/', 'to', 'foo'); // -> 'path/to/foo'
If a part is an absolute path, then anything before that will be ignored:
p.join('path', '/to', 'foo'); // -> '/to/foo'
Implementation
String join(String part1,
        [String? part2,
        String? part3,
        String? part4,
        String? part5,
        String? part6,
        String? part7,
        String? part8,
        String? part9,
        String? part10,
        String? part11,
        String? part12,
        String? part13,
        String? part14,
        String? part15,
        String? part16]) =>
    context.join(part1, part2, part3, part4, part5, part6, part7, part8, part9,
        part10, part11, part12, part13, part14, part15, part16);