code: def check_deps(deps):
          
          if not isinstance(deps, list):
              deps = [deps]
          checks = list(Environment.has_apps(deps))
          if not all(checks):
              for name, available in list(dict(zip(deps, checks)).items()):
                  if not available:
                      error_msg = "The required application/dependency '{0}'" \
                                  " isn't available.".format(name)
                      raise SystemError(error_msg)
docs: check whether specific requirements are available.