_createTrustedTypesPolicy = function _createTrustedTypesPolicy(trustedTypes, purifyHostElement) {
    if (typeof trustedTypes !== 'object' || typeof trustedTypes.createPolicy !== 'function') {
      return null;
    }
    // Allow the callers to control the unique policy name
    // by adding a data-tt-policy-suffix to the script element with the DOMPurify.
    // Policy creation with duplicate names throws in Trusted Types.
    let suffix = null;
    const ATTR_NAME = 'data-tt-policy-suffix';
    if (purifyHostElement && purifyHostElement.hasAttribute(ATTR_NAME)) {
      suffix = purifyHostElement.getAttribute(ATTR_NAME);
    }
    const policyName = 'dompurify' + (suffix ? '#' + suffix : '');
    try {
      return trustedTypes.createPolicy(policyName, {
        createHTML(html) {
          return html;
        },
        createScriptURL(scriptUrl) {
          return scriptUrl;
        }
      });
    } catch (_) {
      // Policy creation failed (most likely another DOMPurify script has
      // already run). Skip creating the policy, as this will only cause errors
      // if TT are enforced.
      console.warn('TrustedTypes policy ' + policyName + ' could not be created.');
      return null;
    }
  }
Creates a no-op policy for internal use only.
Don't export this function outside this module!
@param trustedTypes The policy factory.
@param purifyHostElement The Script element used to load DOMPurify (to determine policy name suffix).
@return The policy created (or null, if Trusted Types
are not supported or creating the policy failed).