general_idea.py

from pyoauth.oauth1 import Credentials
from pyoauth.oauth1.client import Client 

client_credentials = Credentials(
    identifier="CONSUMER KEY",
    shared_secret="CONSUMER SECRET"
)

oauth_client = Client(
    client_credentials,
    temporary_credentials_request_uri="REQUEST TOKEN URL",
    token_credentials_request_uri="ACCESS TOKEN URL",
    resource_owner_authorization_uri="AUTHORIZATION URL",
    use_authorization_header=True      # will use the "Authorization" HTTP header for OAuth parameters.
)

http_client = None  # Use your HTTP client.

class LoginHandler(RequestHandler):
    def get(self):
        
        # Ask the OAuth server for the "request token"
        req = oauth_client.build_temporary_credentials_request(
                    realm="Photos", 
                    oauth_callback="CALLBACK URL"
                )
        response = http_client.request(
            method=req.method,
            payload=req.payload,
            headers=req.headers,
            url=req.url
            )

        # Extract the request token from the OAuth server's response.
        response = ResponseProxy(
                response.status_code, 
                response.status,
                response.body,
                response.headers
            )
        _, request_token = client.parse_temporary_credentials_response(response)


        # Send (redirect) the user to the authorization URL created from the request token.
        self.redirect(client.get_authorization_url(request_token))


# Wait for the browser to return user to your callback URL.
# Handle the callback URL taking these query params out.
# In your callback handler
    
class MyCallbackHandler(RequestHandler):
    def get(self):
        oauth_token = self.request.get('oauth_token')
        oauth_verifier = self.request.get('oauth_verifier')
    
        # You need to check the verification code before you 
        # ask the server for the "access token".
        oauth_client.check_verification_code(request_token, oauth_token, oauth_verifier)
    
        # Now ask for the "Access token".
        req = oauth_client.build_token_credentials_request(
                realm="Photos",
                request_token,
                oauth_verifier
            )
        response = http_client.request(
                method=req.method,
                payload=req.payload,
                headers=req.headers,
                url=req.url
            )
    
        # Extract the "access token" from the response.
        response = ResponseProxy(
                response.status_code, 
                response.status,
                response.body,
                response.headers
            )
        _, access_token = oauth_client.parse_token_credentials_response(response)
        
        # Save this access token to your database somewhere.
        user.access_token = access_token
        user.put()
        
        # To use the access token (in this or any other handler)
        req = oauth_client.build_resource_request(
            access_token,
            url="/api/username",
            method="GET",
        )
        response = http_client.request(
            method=req.method,
            url=req.url,
            headers=req.headers,
            payload=req.payload
        )
        
        # Do what you want with the response here.
        # ....