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

BypassListManagement, FooterSettings, FooterText,
            FooterHtml, SandBoxMode, SpamCheck, SpamThreshold, SpamUrl,
            TrackingSettings, ClickTracking, SubscriptionTracking,
            SubscriptionText, SubscriptionHtml, SubscriptionSubstitutionTag,
            OpenTracking, OpenTrackingSubstitutionTag, Ganalytics,
            UtmSource, UtmMedium, UtmTerm, UtmContent, UtmCampaign)

        self.maxDiff = None

        message = Mail()

        # Define Personalizations

        message.to = To('test1@example.com', 'Example User1', p=0)
        message.to = [
            To('test2@example.com', 'Example User2', p=0),
            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)

def test_single_email_to_a_single_recipient_with_dynamic_templates(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.dynamic_template_data = DynamicTemplateData({
            "total": "$ 239.85",
            "items": [
                {
                    "text": "New Line Sneakers",
                    "image": "https://marketing-image-production.s3.amazonaws.com/uploads/8dda1131320a6d978b515cc04ed479df259a458d5d45d58b6b381cae0bf9588113e80ef912f69e8c4cc1ef1a0297e8eefdb7b270064cc046b79a44e21b811802.png",
                    "price": "$ 79.95"
                },
                {
                    "text": "Old Line Sneakers",
                    "image": "https://marketing-image-production.s3.amazonaws.com/uploads/3629f54390ead663d4eb7c53702e492de63299d7c5f7239efdc693b09b9b28c82c924225dcd8dcb65732d5ca7b7b753c5f17e056405bbd4596e4e63a96ae5018.png",

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'),

SpamCheck, SpamThreshold, SpamUrl, TrackingSettings,
        ClickTracking, SubscriptionTracking, SubscriptionText,
        SubscriptionHtml, SubscriptionSubstitutionTag,
        OpenTracking, OpenTrackingSubstitutionTag, Ganalytics,
        UtmSource, UtmMedium, UtmTerm, UtmContent, UtmCampaign)
    import time
    import datetime

    message = Mail()

    # Define Personalizations 

    message.to = To('test1@sendgrid.com', 'Example User1', p=0)
    message.to = [ 
        To('test2@sendgrid.com', 'Example User2', p=0),
        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)

Substitution('%city2%', 'Example City 2', p=0)
    ]

    message.custom_arg = CustomArg('marketing1', 'true', p=0)
    message.custom_arg = CustomArg('transactional1', 'false', p=0)
    message.custom_arg = [
        CustomArg('marketing2', 'false', p=0),
        CustomArg('transactional2', 'true', p=0)
    ]

    message.send_at = SendAt(1461775051, p=0)

    message.to = To('test10@example.com', 'Example User10', p=1)
    message.to = [ 
        To('test11@example.com', 'Example User11', p=1),
        To('test12@example.com', 'Example User12', p=1)
    ]

    message.cc = Cc('test13@example.com', 'Example User13', p=1)
    message.cc = [ 
        Cc('test14@example.com', 'Example User14', p=1),
        Cc('test15@example.com', 'Example User15', p=1)
    ]

    message.bcc = Bcc('test16@example.com', 'Example User16', p=1)
    message.bcc = [ 
        Bcc('test17@example.com', 'Example User17', p=1),
        Bcc('test18@example.com', 'Example User18', p=1)
    ]

    message.header = Header('X-Test5', 'Test5', p=1)
    message.header = Header('X-Test6', 'Test6', p=1)

Substitution('%name2%', 'Example Name 2', p=0),
        Substitution('%city2%', 'Example City 2', p=0)
    ]

    message.custom_arg = CustomArg('marketing1', 'true', p=0)
    message.custom_arg = CustomArg('transactional1', 'false', p=0)
    message.custom_arg = [
        CustomArg('marketing2', 'false', p=0),
        CustomArg('transactional2', 'true', p=0)
    ]

    message.send_at = SendAt(1461775051, p=0)

    message.to = To('test10@example.com', 'Example User10', p=1)
    message.to = [ 
        To('test11@example.com', 'Example User11', p=1),
        To('test12@example.com', 'Example User12', p=1)
    ]

    message.cc = Cc('test13@example.com', 'Example User13', p=1)
    message.cc = [ 
        Cc('test14@example.com', 'Example User14', p=1),
        Cc('test15@example.com', 'Example User15', p=1)
    ]

    message.bcc = Bcc('test16@example.com', 'Example User16', p=1)
    message.bcc = [ 
        Bcc('test17@example.com', 'Example User17', p=1),
        Bcc('test18@example.com', 'Example User18', p=1)
    ]

    message.header = Header('X-Test5', 'Test5', p=1)

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.custom_arg = CustomArg('transactional1', 'false', p=0)
    message.custom_arg = [
        CustomArg('marketing2', 'false', p=0),
        CustomArg('transactional2', 'true', p=0)
    ]

    message.send_at = SendAt(1461775051, p=0)

    message.to = To('test10@example.com', 'Example User10', p=1)
    message.to = [ 
        To('test11@example.com', 'Example User11', p=1),
        To('test12@example.com', 'Example User12', p=1)
    ]

    message.cc = Cc('test13@example.com', 'Example User13', p=1)
    message.cc = [ 
        Cc('test14@example.com', 'Example User14', p=1),
        Cc('test15@example.com', 'Example User15', p=1)
    ]

    message.bcc = Bcc('test16@example.com', 'Example User16', p=1)
    message.bcc = [ 
        Bcc('test17@example.com', 'Example User17', p=1),
        Bcc('test18@example.com', 'Example User18', p=1)
    ]

GroupId, GroupsToDisplay, IpPoolName, MailSettings,
        BccSettings, BccSettingsEmail, BypassListManagement,
        FooterSettings, FooterText, FooterHtml, SandBoxMode,
        SpamCheck, SpamThreshold, SpamUrl, TrackingSettings,
        ClickTracking, SubscriptionTracking, SubscriptionText,
        SubscriptionHtml, SubscriptionSubstitutionTag,
        OpenTracking, OpenTrackingSubstitutionTag, Ganalytics,
        UtmSource, UtmMedium, UtmTerm, UtmContent, UtmCampaign)
    import time
    import datetime

    message = Mail()

    # Define Personalizations 

    message.to = To('test1@sendgrid.com', 'Example User1', p=0)
    message.to = [ 
        To('test2@sendgrid.com', 'Example User2', p=0),
        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)
    ]

FooterSettings, FooterText, FooterHtml, SandBoxMode,
        SpamCheck, SpamThreshold, SpamUrl, TrackingSettings,
        ClickTracking, SubscriptionTracking, SubscriptionText,
        SubscriptionHtml, SubscriptionSubstitutionTag,
        OpenTracking, OpenTrackingSubstitutionTag, Ganalytics,
        UtmSource, UtmMedium, UtmTerm, UtmContent, UtmCampaign)
    import time
    import datetime

    message = Mail()

    # Define Personalizations 

    message.to = To('test1@sendgrid.com', 'Example User1', p=0)
    message.to = [ 
        To('test2@sendgrid.com', 'Example User2', p=0),
        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)

"""
        Create a Mail object from an instance of email.message.EmailMessage.

        This is a copy and tweak of Mail.from_EmailMessage from the SendGrid SDK
        to get around a bug where it creates an Email object and later requires
        that object to be an instance of a To, Cc, or Bcc object.

        It also strips out any reserved key headers on the message object.
        """

        mail = Mail(
            from_email=Email(message.get('From')),
            subject=message.get('Subject'),

            # Create a To object instead of an Email object
            to_emails=To(message.get('To')),
        )
        try:
            body = message.get_content()
        except AttributeError:
            # Python2
            body = message.get_payload(decode=True).decode('utf-8')
        mail.add_content(Content(
            message.get_content_type(),
            body.strip()
        ))

        # These headers are not allowed on the message object
        # https://sendgrid.com/docs/API_Reference/Web_API_v3/Mail/errors.html#message.headers
        skip_headers = [
            'x-sg-id', 'x-sg-eid', 'received', 'dkim-signature', 'Content-Type',
            'Content-Transfer-Encoding', 'To', 'From', 'Subject', 'Reply-To', 'CC', 'BCC'