Env constructor
Env()
Implementation
Env() {
argParser.addFlag('new',
abbr: 'n', negatable: false, help: 'Create a new environment variable.');
argParser.addFlag('ref',
abbr: 'r', negatable: false, help: 'Refresh the dart class file.');
argParser.addFlag('delete',
abbr: 'd', negatable: false, help: 'Delete the environment variable.');
}