lib.strings.normalizePath

The following is the current implementation of this function.

s:
    if isPath s then
      throw ''
        lib.strings.normalizePath: The argument (${toString s}) is a path value, but only strings are supported.
            Path values are always normalised in Nix, so there's no need to call this function on them.''
    else
      builtins.foldl' (x: y: if y == "/" && startsWithSlash x then x else x + y) "" (
        stringToCharacters s
      )