# Pastebin vQbHAwOg
  new val create(base: (FilePath | AmbientAuth), path': String,
    caps': FileCaps val = recover val FileCaps.>all() end) ?
  =>
    """
    Create a new path. The caller must either provide the root capability or an
    existing FilePath.

    If the root capability is provided, path' will be relative to the program's
    working directory. Otherwise, it will be relative to the existing FilePath,
    and the existing FilePath must be a prefix of the resulting path.

    The resulting FilePath will have capabilities that are the intersection of
    the supplied capabilities and the capabilities on the parent.
    """
    caps.union(caps')