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

}
        else if (o === 'parameters') {
            // checked above
        }
        else if (o === 'servers') {
            contextAppend(options, 'servers');
            checkServers(op, options); // won't be here in converted definitions
            options.context.pop();
        }
        else if (o === 'summary') {
            should(pathItem.summary).have.type('string');
        }
        else if (o === 'description') {
            should(pathItem.description).have.type('string');
        }
        else if (common.httpMethods.indexOf(o) >= 0) {
            should(op).be.an.Object();
            should(op).not.be.an.Array();
            should(op).not.have.property('consumes');
            should(op).not.have.property('produces');
            should(op).not.have.property('schemes');
            should(op).have.property('responses');
            should(op.responses).not.be.undefined();
            should(op.responses).be.an.Object();
            should(op.responses).not.be.an.Array();
            should(op.responses).not.be.empty();
            if (typeof op.summary !== 'undefined') should(op.summary).have.type('string');
            if (typeof op.description !== 'undefined') should(op.description).be.a.String();
            if (typeof op.operationId !== 'undefined') {
                should(op.operationId).be.a.String();
                should(options.operationIds.indexOf(op.operationId)).be.exactly(-1,'operationIds must be unique ['+op.operationId+']');
                options.operationIds.push(op.operationId);

delete path['x-trace'];
        }
        if (path && (path['x-summary']) && (typeof path['x-summary'] === 'string')) {
            path.summary = path['x-summary'];
            delete path['x-summary'];
        }
        if (path && (path['x-description']) && (typeof path['x-description'] === 'string')) {
            path.description = path['x-description'];
            delete path['x-description'];
        }
        if (path && (path['x-servers']) && (Array.isArray(path['x-servers']))) {
            path.servers = path['x-servers'];
            delete path['x-servers'];
        }
        for (let method in path) {
            if ((common.httpMethods.indexOf(method) >= 0) || (method === 'x-amazon-apigateway-any-method')) {
                let op = path[method];

                if (op && op.parameters && Array.isArray(op.parameters)) {
                    if (path.parameters) {
                        for (let param of path.parameters) {
                            if (typeof param.$ref === 'string') {
                                fixParamRef(param, options);
                                param = resolveInternal(openapi, param.$ref);
                            }
                            let match = op.parameters.find(function (e, i, a) {
                                return ((e.name === param.name) && (e.in === param.in));
                            });

                            if (!match && ((param.in === 'formData') || (param.in === 'body') || (param.type === 'file'))) {
                                op = processParameter(param, op, path, method, p, openapi, options);
                                if (options.rbname && op[options.rbname] === '') {