code: def make_cursor(self, path_or_fd):
          
          regions = self._fdict.get(path_or_fd)
          if regions is None:
              regions = self.MapRegionListCls(path_or_fd)
              self._fdict[path_or_fd] = regions
          # END obtain region for path
          return self.WindowCursorCls(self, regions)
docs: :return: a cursor pointing to the given path or file descriptor.
              It can be used to map new regions of the file into memory
  
          **Note:** if a file descriptor is given, it is assumed to be open and valid,
          but may be closed afterwards. To refer to the same file, you may reuse
          your existing file descriptor, but keep in mind that new windows can only
          be mapped as long as it stays valid. This is why the using actual file paths
          are preferred unless you plan to keep the file descriptor open.
  
          **Note:** file descriptors are problematic as they are not necessarily unique, as two
          different files opened and closed in succession might have the same file descriptor id.
  
          **Note:** Using file descriptors directly is faster once new windows are mapped as it
          prevents the file to be opened again just for the purpose of mapping it.