code: function getDirective(path) {
      for (let directive of path.node.directives) {
        let dirstr = directive.value.value
        if (dirstr.startsWith('use ')) {
          let uses = dirstr.substr(4).split(',').map((use) => use.trim())
          if (uses.indexOf('extensible') !== -1) {
            return 1
          }
          if (uses.indexOf('!extensible') !== -1) {
            return -1
          }
        }
      }
      return 0
    }
docs: 0 - no directive 1 - 'use extensible' directive -1 - 'use !extensible' directive