message: Fix optional indentation.
diff: @@ -32,7 +32,7 @@ def process_ifs(lines, onnx_ml):
  yield line
  PROTO_SYNTAX_REGEX = re.compile(r'(\s*)syntax\s*=\s*"proto2"\s*;\s*$')
  -OPTIONAL_REGEX = re.compile(r'(\s*)optional(\s.*)$')
  +OPTIONAL_REGEX = re.compile(r'(\s*)optional\s(.*)$')
  def convert_to_proto3(lines):
  for line in lines:
  