How to use the oas-kit-common.uniqueOnly function in oas-kit-common

function processParameter(param, op, path, method, index, openapi, options) {
    let result = {};
    let singularRequestBody = true;
    let originalType;

    if (op && op.consumes && (typeof op.consumes === 'string')) {
        if (options.patch) {
            op.consumes = [op.consumes];
        }
        else {
            return throwError('(Patchable) operation.consumes must be an array', options);
        }
    }
    if (!Array.isArray(openapi.consumes)) delete openapi.consumes;
    let consumes = ((op ? op.consumes : null) || (openapi.consumes || [])).filter(common.uniqueOnly);

    if (param && param.$ref && (typeof param.$ref === 'string')) {
        // if we still have a ref here, it must be an internal one
        fixParamRef(param, options);
        let ptr = decodeURIComponent(param.$ref.replace('#/components/parameters/', ''));
        let rbody = false;
        let target = openapi.components.parameters[ptr]; // resolves a $ref, must have been sanitised already

        if (((!target) || (target["x-s2o-delete"])) && param.$ref.startsWith('#/')) {
            // if it's gone, chances are it's a requestBody component now unless spec was broken
            param["x-s2o-delete"] = true;
            rbody = true;
        }

        // shared formData parameters from swagger or path level could be used in any combination.
        // we dereference all op.requestBody's then hash them and pull out common ones later

else {
                if (options.lint) options.linter('reference',link,'$ref',options);
            }
            options.context.pop();
        }
        options.context.pop();
    }

    if (!options.validateSchema || (options.validateSchema === 'last')) {
        schemaValidate(openapi, options);
    }

    options.valid = !options.expectFailure;
    if (options.lint) options.linter('openapi',openapi,'',options);

    options.warnings = options.warnings.filter(common.uniqueOnly);

    if (options.verbose > 1) {
        for (let w=0;w options.lintLimit ? `, showing first ${options.lintLimit}` : ''}`);