normalize

Normalizes the segments of a URL path according to the following rules:

• The returned path always begins with / (e.g., a/b/c → /a/b/c)

• The returned path ends with / if the input path also does

• Empty segments are discarded (e.g., /a//b → /a/b)

• Segments of . are discarded (e.g., /a/./b → /a/b)

• Segments of .. are used to discard ancestor paths (e.g., /a/b/../c → /a/c)

• All other segments are unmodified