. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 1.11 Configuration Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 1.12 Signals implemented in Flask itself. Numerous extensions provide database integration, form validation, upload handling, various open authentication technologies, and more. Flask may be “micro”, but it’s ready for pro- not exist, there are multiple reasons this might be the case. First of all you need to look at the error message. Old Version of Flask Versions of Flask older than 0.11 used to have different ways to start

Accessing and Modifying Sessions Testing JSON APIs Testing CLI Commands Application Errors Error Logging Tools Error handlers Logging Debugging Application Errors When in Doubt, Run Manually Working with Configuration Email Errors to Admins Injecting Request Information Other Libraries Configuration Handling Configuration Basics Environment and Debug Features Builtin Configuration Values Configuring from Preservation on Error Notes On Proxies Modular Applications with Blueprints Why Blueprints? The Concept of Blueprints My First Blueprint Registering Blueprints Blueprint Resources Building URLs Error Handlers

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 1.15 Exception Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 1.16 Python values • is fully nestable and composable • works the same in Python 2 and 3 • supports file handling out of the box • comes with useful common helpers (getting terminal dimensions, ANSI colors, fetching nesting of commands by design and has some deficiencies when it comes to POSIX compliant argument handling. Click is designed to be fun to work with and at the same time not stand in your way. It’s not

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 1.15 Exception Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 1.16 Python values • is fully nestable and composable • works the same in Python 2 and 3 • supports file handling out of the box • comes with useful common helpers (getting terminal dimensions, ANSI colors, fetching nesting of commands by design and has some deficiencies when it comes to POSIX compliant argument handling. Click is designed to be fun to work with and at the same time not stand in your way. It’s not

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 1.15 Exception Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 1.16 Python values • is fully nestable and composable • works the same in Python 2 and 3 • supports file handling out of the box • comes with useful common helpers (getting terminal dimensions, ANSI colors, fetching nesting of commands by design and has some deficiencies when it comes to POSIX compliant argument handling. Click is designed to be fun to work with and at the same time not stand in your way. It’s not

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 1.15 Exception Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 1.16 Python values • is fully nestable and composable • works the same in Python 2 and 3 • supports file handling out of the box • comes with useful common helpers (getting terminal dimensions, ANSI colors, fetching nesting of commands by design and has some deficiencies when it comes to POSIX compliant argument handling. Click is designed to be fun to work with and at the same time not stand in your way. It’s not

log — Logging support tornado.options — Command-line parsing tornado.stack_context — Exception handling across asynchronous callbacks tornado.testing — Unit testing support for asynchronous code tornado web application The Application object Subclassing RequestHandler Handling request input Overriding RequestHandler methods Error Handling Redirection Asynchronous handlers Templates and UI Configuring they have two major advantages. Error handling is more consistent since the Future.result method can simply raise an exception (as opposed to the ad-hoc error handling common in callback-oriented interfaces)

You do not need to navigate to the Anaconda directory. EXAMPLE: conda 4.7.12 Note: If you get an error message, make sure you closed and re-opened the terminal window after installing, or do it now. Then /usr/share/keyrings/conda-archive-keyring.gpg # Check whether fingerprint is correct (will output an error message otherwise) gpg --keyring /usr/share/keyrings/conda-archive-keyring.gpg --no-default-keyring stable main" > /etc/apt/sources.list.d/conda. ˓→list **NB:** If you receive a Permission denied error when trying to run the above command␣ ˓→(because �/etc/apt/sources.list.d/conda.list� is write protected)

You do not need to navigate to the Anaconda directory. EXAMPLE: conda 4.7.12 Note: If you get an error message, make sure you closed and re-opened the terminal window after installing, or do it now. Then /usr/share/keyrings/conda-archive-keyring.gpg # Check whether fingerprint is correct (will output an error message otherwise) gpg --keyring /usr/share/keyrings/conda-archive-keyring.gpg --no-default-keyring stable main" > /etc/apt/sources.list.d/conda. ˓→list **NB:** If you receive a Permission denied error when trying to run the above command␣ ˓→(because �/etc/apt/sources.list.d/conda.list� is write protected)

tornado.log — Logging support tornado.options — Command-line parsing tornado.stack_context — Exception handling across asynchronous callbacks tornado.testing — Unit testing support for asynchronous code tornado web application The Application object Subclassing RequestHandler Handling request input Overriding RequestHandler methods Error Handling Redirection Asynchronous handlers Templates and UI Configuring your code in the same way you would if it were synchronous. This is especially important for error handling, since try/except blocks work as you would expect in coroutines while this is difficult to achieve