whole_func_string: function thunk(formula) {
          var evaluated = false,
              value;
          return function() {
              if (evaluated === false) { value = formula(); evaluated = true; }
              return value;
          };
      }
func_code_string: function thunk(formula) {
          var evaluated = false,
              value;
          return function() {
              if (evaluated === false) { value = formula(); evaluated = true; }
              return value;
          };
      }
func_documentation_string: A simple implementation of a thunk
  @param formula function used to lazily initialize the thunk
  @return {Function}