code: def ReadVFS(pathspec, offset, length, progress_callback=None):
    
    fd = VFSOpen(pathspec, progress_callback=progress_callback)
    fd.Seek(offset)
    return fd.Read(length)
docs: Read from the VFS and return the contents.
  
    Args:
      pathspec: path to read from
      offset: number of bytes to skip
      length: number of bytes to read
      progress_callback: A callback to indicate that the open call is still
        working but needs more time.
  
    Returns:
      VFS file contents