Package errors provides extended error handling. When you need to retain more information about an error message than a single string allows, just substitute this package for the one in the standard library. The `New` function still accepts a single string as argument, so no code will be broken. Where you need to include additional information, you can provide it to `New` in a `Desc` structure instead of the string, or you can add it to the error message using one of its setter methods. The additional information can be used for smarter error handling and logging: - `Level` differentiates between warnings, regular errors, panics converted to errors, and fatal errors; - `Code` allows custom classification and prioritizing, by using ranges or bit-level masks; - `Info` offers a store for arbitrary data and messages, besides the main error `Text`; the special string "debug.stack", if present as an element in the Info slice, is automatically replaced by a stack trace at the point the error message has been created.