GetEnv reads a file expected to represent a collection of KEY=value in
standard shell environment variable format - i.e., key usually in all upper
case no spaces and words separated by underscore; value can have any
separator, but usually comma, for an array of values.
LookupEnv returns the raw string value associated with a provided key name,
used as a custom environment variable loader for go-simpler.org/env to enable
.env file loading.