code: function(opts) {
      if (!opts) {
        throw new Error.StripeError({
          message: 'Options are required',
        });
      }
  
      opts.timestamp = Math.floor(opts.timestamp) || Math.floor(Date.now() / 1000);
      opts.scheme = opts.scheme || signature.EXPECTED_SCHEME;
  
      opts.signature = opts.signature ||
        signature._computeSignature(opts.timestamp + '.' + opts.payload, opts.secret);
  
      var generatedHeader = [
        't=' + opts.timestamp,
        opts.scheme + '=' + opts.signature,
      ].join(',');
  
      return generatedHeader;
    }
docs: Generates a header to be used for webhook mocking
  
  @typedef {object} opts
  @property {number} timestamp - Timestamp of the header. Defaults to Date.now()
  @property {string} payload - JSON stringified payload object, containing the 'id' and 'object' parameters
  @property {string} secret - Stripe webhook secret 'whsec_...'
  @property {string} scheme - Version of API to hit. Defaults to 'v1'.
  @property {string} signature - Computed webhook signature