class copy :?depth:Webdav_http.depth -> ?overwrite:bool -> ?strip_prefix:string -> string -> string ->copy_call_t
new copy src_url dest_url: Copies the object(s) at src_url
      so that they become visible at dest_url. This works for documents,
      collections, or whole subtrees.
      The dest_url needs to be the full URL, including the 
      http://server prefix.
depth: If set to `Zero, only the single object at src_url
        is copied without member objects (in case of collections).
        If set to `Infinity, the whole subtree is copied.
        The depth value of `One is illegal. If missing servers usually
        assume `Infinity.overwrite: Whether it is allowed to overwrite destination
        objects. If missing servers usually assume true.