whole_func_string: function writeYamlFile(file, data, cb) {
    fs.writeFile(file, yaml.safeDump(data), () => {
      if (cb) cb();
    });
  }
func_code_string: function writeYamlFile(file, data, cb) {
    fs.writeFile(file, yaml.safeDump(data), () => {
      if (cb) cb();
    });
  }
func_documentation_string: Write Yaml string to File
  @param {string} file - File path
  @param {object} data - Object to turn into Yaml
  @param {function} cb - Optional callback when done
  @see writeYamlFileSync