static parse(permissions) {
        const blobSASPermissions = new BlobSASPermissions();
        for (const char of permissions) {
            switch (char) {
                case "r":
                    blobSASPermissions.read = true;
                    break;
                case "a":
                    blobSASPermissions.add = true;
                    break;
                case "c":
                    blobSASPermissions.create = true;
                    break;
                case "w":
                    blobSASPermissions.write = true;
                    break;
                case "d":
                    blobSASPermissions.delete = true;
                    break;
                case "x":
                    blobSASPermissions.deleteVersion = true;
                    break;
                case "t":
                    blobSASPermissions.tag = true;
                    break;
                case "m":
                    blobSASPermissions.move = true;
                    break;
                case "e":
                    blobSASPermissions.execute = true;
                    break;
                case "i":
                    blobSASPermissions.setImmutabilityPolicy = true;
                    break;
                case "y":
                    blobSASPermissions.permanentDelete = true;
                    break;
                default:
                    throw new RangeError(`Invalid permission: ${char}`);
            }
        }
        return blobSASPermissions;
    }
Creates a {@link BlobSASPermissions} from the specified permissions string. This method will throw an
Error if it encounters a character that does not correspond to a valid permission.

@param permissions -