Returns the bool value of environment variable "key" or the default value if "key" is not set.

Returns the duration value of environment variable "key" or a default value Note if the environment variable cannot be parsed as a duration, including an empty string, this will fail and exit.

Returns the integer of value environment variable "key" or the default value if "key" is not set.

Returns the string value of environment variable "key" or the default value if "key" is not set.