How to use the @angular/language-service/src/diagnostics.getDeclarationDiagnostics function in @angular/language-service

LanguageServiceImpl.prototype.getDiagnostics = function (fileName) {
            var results = [];
            var templates = this.host.getTemplates(fileName);
            if (templates && templates.length) {
                results.push.apply(results, tslib_1.__spread(diagnostics_1.getTemplateDiagnostics(fileName, this, templates)));
            }
            var declarations = this.host.getDeclarations(fileName);
            if (declarations && declarations.length) {
                var summary = this.host.getAnalyzedModules();
                results.push.apply(results, tslib_1.__spread(diagnostics_1.getDeclarationDiagnostics(declarations, summary)));
            }
            return uniqueBySpan(results);
        };
        LanguageServiceImpl.prototype.getPipesAt = function (fileName, position) {