proc writeFile*(filename: string, content: openarray[byte]) =
  ## Opens a file named `filename` for writing. Then writes the
  ## `content` completely to the file and closes the file afterwards.
  ## Raises an IO exception in case of an error.
  var f: File
  if open(f, filename, fmWrite):
    try:
      f.writeBuffer(unsafeAddr content[0], content.len)
    finally:
      close(f)
  else:
    raise newException(IOError, "cannot open: " & filename)