How to use the sendgrid.helpers.mail.Subject function in sendgrid

def test_single_email_to_a_single_recipient_content_reversed(self):
        """Tests bug found in Issue-451 with Content ordering causing a crash
        """
        from sendgrid.helpers.mail import (Mail, From, To, Subject,
                                           PlainTextContent, HtmlContent)
        self.maxDiff = None
        message = Mail()
        message.from_email = From('test+from@example.com', 'Example From Name')
        message.to = To('test+to@example.com', 'Example To Name')
        message.subject = Subject('Sending with SendGrid is Fun')
        message.content = HtmlContent(
            '<strong>and easy to do anywhere, even with Python</strong>')
        message.content = PlainTextContent(
            'and easy to do anywhere, even with Python')

        self.assertEqual(
            message.get(),
            json.loads(r'''{
                "content": [

message.substitution = Substitution('%city3%', 'Example City 3', p=1)
        message.substitution = [
            Substitution('%name4%', 'Example Name 4', p=1),
            Substitution('%city4%', 'Example City 4', p=1)
        ]

        message.custom_arg = CustomArg('marketing3', 'true', p=1)
        message.custom_arg = CustomArg('transactional3', 'false', p=1)
        message.custom_arg = [
            CustomArg('marketing4', 'false', p=1),
            CustomArg('transactional4', 'true', p=1)
        ]

        message.send_at = SendAt(1461775052, p=1)

        message.subject = Subject('Sending with SendGrid is Fun 1', p=1)

        # The values below this comment are global to entire message

        message.from_email = From('dx@example.com', 'DX')

        message.reply_to = ReplyTo('dx_reply@example.com', 'DX Reply')

        message.subject = Subject('Sending with SendGrid is Fun 2')

        message.content = Content(
            MimeType.text,
            'and easy to do anywhere, even with Python')
        message.content = Content(
            MimeType.html,
            '<strong>and easy to do anywhere, even with Python</strong>')
        message.content = [

message.custom_arg = [
            CustomArg('marketing4', 'false', p=1),
            CustomArg('transactional4', 'true', p=1)
        ]

        message.send_at = SendAt(1461775052, p=1)

        message.subject = Subject('Sending with SendGrid is Fun 1', p=1)

        # The values below this comment are global to entire message

        message.from_email = From('dx@example.com', 'DX')

        message.reply_to = ReplyTo('dx_reply@example.com', 'DX Reply')

        message.subject = Subject('Sending with SendGrid is Fun 2')

        message.content = Content(
            MimeType.text,
            'and easy to do anywhere, even with Python')
        message.content = Content(
            MimeType.html,
            '<strong>and easy to do anywhere, even with Python</strong>')
        message.content = [
            Content('text/calendar', 'Party Time!!'),
            Content('text/custom', 'Party Time 2!!')
        ]

        message.attachment = Attachment(
            FileContent('base64 encoded content 1'),
            FileName('balance_001.pdf'),
            FileType('application/pdf'),

def test_unicode_values_in_substitutions_helper(self):
        from sendgrid.helpers.mail import (Mail, From, To, Subject,
                                           PlainTextContent, HtmlContent)
        self.maxDiff = None
        message = Mail(
            from_email=From('test+from@example.com', 'Example From Name'),
            to_emails=To('test+to@example.com', 'Example To Name'),
            subject=Subject('Sending with SendGrid is Fun'),
            plain_text_content=PlainTextContent(
                'and easy to do anywhere, even with Python'),
            html_content=HtmlContent(
                '<strong>and easy to do anywhere, even with Python</strong>'))
        message.substitution = Substitution('%city%', u'Αθήνα', p=1)
        self.assertEqual(
            message.get(),
            json.loads(r'''{
                "content": [

def test_multiple_emails_to_multiple_recipients(self):
        from sendgrid.helpers.mail import (Mail, From, To, Subject,
                                           PlainTextContent, HtmlContent,
                                           Substitution)
        self.maxDiff = None

        to_emails = [
            To(email='test+to0@example.com',
                name='Example Name 0',
                substitutions=[
                    Substitution('-name-', 'Example Name Substitution 0'),
                    Substitution('-github-', 'https://example.com/test0'),
                ],
                subject=Subject('Override Global Subject')),
            To(email='test+to1@example.com',
                name='Example Name 1',
                substitutions=[
                    Substitution('-name-', 'Example Name Substitution 1'),
                    Substitution('-github-', 'https://example.com/test1'),
                ])
        ]
        global_substitutions = Substitution('-time-', '2019-01-01 00:00:00')
        message = Mail(
            from_email=From('test+from@example.com', 'Example From Name'),
            to_emails=to_emails,
            subject=Subject('Hi -name-'),
            plain_text_content=PlainTextContent(
                'Hello -name-, your URL is -github-, email sent at -time-'),
            html_content=HtmlContent(
                '<strong>Hello -name-, your URL is <a href="\&quot;-github-\&quot;">here</a></strong> email sent at -time-'),

To('test3@example.com', 'Example User3', p=0)
        ]

        message.cc = Cc('test4@example.com', 'Example User4', p=0)
        message.cc = [
            Cc('test5@example.com', 'Example User5', p=0),
            Cc('test6@example.com', 'Example User6', p=0)
        ]

        message.bcc = Bcc('test7@example.com', 'Example User7', p=0)
        message.bcc = [
            Bcc('test8@example.com', 'Example User8', p=0),
            Bcc('test9@example.com', 'Example User9', p=0)
        ]

        message.subject = Subject('Sending with SendGrid is Fun 0', p=0)

        message.header = Header('X-Test1', 'Test1', p=0)
        message.header = Header('X-Test2', 'Test2', p=0)
        message.header = [
            Header('X-Test3', 'Test3', p=0),
            Header('X-Test4', 'Test4', p=0)
        ]

        message.substitution = Substitution('%name1%', 'Example Name 1', p=0)
        message.substitution = Substitution('%city1%', 'Example City 1', p=0)
        message.substitution = [
            Substitution('%name2%', 'Example Name 2', p=0),
            Substitution('%city2%', 'Example City 2', p=0)
        ]

        message.custom_arg = CustomArg('marketing1', 'true', p=0)

def send(to_email, subject, html_content):
  """Send email."""
  sendgrid_api_key = db_config.get_value('sendgrid_api_key')
  if not sendgrid_api_key:
    logs.log_warn('Skipping email as SendGrid API key is not set in config.')
    return

  from_email = db_config.get_value('sendgrid_sender')
  if not from_email:
    logs.log_warn('Skipping email as SendGrid sender is not set in config.')
    return

  message = Mail(
      from_email=From(str(from_email)),
      to_emails=To(str(to_email)),
      subject=Subject(subject),
      html_content=HtmlContent(str(html_content)))
  try:
    sg = SendGridAPIClient(sendgrid_api_key)
    response = sg.send(message)
    logs.log(
        'Sent email to %s.' % to_email,
        status_code=response.status_code,
        body=response.body,
        headers=response.headers)
  except Exception:
    logs.log_error('Failed to send email to %s.' % to_email)

To('test3@sendgrid.com', 'Example User3', p=0)
    ]

    message.cc = Cc('test4@example.com', 'Example User4', p=0)
    message.cc = [ 
        Cc('test5@example.com', 'Example User5', p=0),
        Cc('test6@example.com', 'Example User6', p=0)
    ]

    message.bcc = Bcc('test7@example.com', 'Example User7', p=0)
    message.bcc = [ 
        Bcc('test8@example.com', 'Example User8', p=0),
        Bcc('test9@example.com', 'Example User9', p=0)
    ]

    message.subject = Subject('Sending with SendGrid is Fun 0', p=0)

    message.header = Header('X-Test1', 'Test1', p=0)
    message.header = Header('X-Test2', 'Test2', p=0)
    message.header = [
        Header('X-Test3', 'Test3', p=0),
        Header('X-Test4', 'Test4', p=0)
    ]

    message.substitution = Substitution('%name1%', 'Example Name 1', p=0)
    message.substitution = Substitution('%city1%', 'Example City 1', p=0)
    message.substitution = [
        Substitution('%name2%', 'Example Name 2', p=0),
        Substitution('%city2%', 'Example City 2', p=0)
    ]

    message.custom_arg = CustomArg('marketing1', 'true', p=0)

message.substitution = Substitution('%city3%', 'Example City 3', p=1)
    message.substitution = [
        Substitution('%name4%', 'Example Name 4', p=1),
        Substitution('%city4%', 'Example City 4', p=1)
    ]

    message.custom_arg = CustomArg('marketing3', 'true', p=1)
    message.custom_arg = CustomArg('transactional3', 'false', p=1)
    message.custom_arg = [
        CustomArg('marketing4', 'false', p=1),
        CustomArg('transactional4', 'true', p=1)
    ]

    message.send_at = SendAt(1461775052, p=1)

    message.subject = Subject('Sending with SendGrid is Fun 1', p=1)

    # The values below this comment are global to entire message

    message.from_email = From('dx@sendgrid.com', 'DX')

    message.reply_to = ReplyTo('dx_reply@sendgrid.com', 'DX Reply')

    message.subject = Subject('Sending with SendGrid is Fun 2')

    message.content = Content(MimeType.text, 'and easy to do anywhere, even with Python')
    message.content = Content(MimeType.html, '<strong>and easy to do anywhere, even with Python</strong>')
    message.content = [
        Content('text/calendar', 'Party Time!!'),
        Content('text/custom', 'Party Time 2!!')
    ]