Bool registers a flag and returns the pointer to the resulting boolean.
The default value is passed as fallback and env sets the env variable
that can override the default.
Duration registers a flag and returns the pointer to the resulting duration.
The default value is passed as fallback and env sets the env variable
that can override the default.
Int registers a flag and returns the pointer to the resulting int.
The default value is passed as fallback and env sets the env variable
that can override the default.
func String(name, env, fallback, help string) *string
String registers a flag and returns the pointer to the resulting string.
The default value is passed as fallback and env sets the env variable
that can override the default.