Application.fetch_env-exclamation-mark

You're seeing just the function fetch_env-exclamation-mark, go back to Application module for more information.

Specs

fetch_env!(app(), key()) :: value()

Returns the value for key in app's environment.

If the configuration parameter does not exist, raises ArgumentError.

Important: if you are reading the application environment at compilation time, for example, inside the module definition instead of inside of a function, see compile_env!/2 instead.