python报错是标点符号错误

request_header3 = "UserMsg-length: { "request_type ": "register ","production_line_number ": 1}\r\n"
  File "<stdin>", line 1
    request_header3 = "UserMsg-length: { "request_type ": "register ","production_line_number ": 1}\r\n"
                                                     ^
SyntaxError: invalid syntax

三引号或者单引号

request_header3 = """UserMsg-length: { "request_type ": "register ","production_line_number ": 1}\r\n"""
request_header3 = 'request_header3 = """UserMsg-length: { "request_type ": "register ","production_line_number ": 1}\r\n'