Use collection JS function from collection requests

My question:
Some of my collection requests (but not all) has to to execute the same functions (the difference is only in parameters). I’d like to define js function with parameters into collection level (for example, into collection pre-request script) and use it from pre-request scripts of collection requests. I try to do it:

and use this function from collection pre-request script:

but encountered with an error:
ReferenceError: getToken is not defined

What am I doing wrong?

Details (like screenshots):
common pre-request collection function:

function getToken(email, password, tokenVariable) {
        url: pm.environment.get("serviceUri") + '/api/v1/auth',
        method: 'POST',
        header: {
            'accept': 'text/plain',
            'Content-Type': 'application/json-patch+json'
        body: {
            mode: 'raw',
            raw: JSON.stringify({ 'email': email, 'password': password })
    }, (error, response) => {

        pm.test("Success", () => {
            pm.expect(response)'code', 200);

        pm.variables.set(tokenVariable, response.text());

pre-request script from collection request usage:

getToken(pm.variables.get("userEmail"), pm.variables.get("userPassword"), "userToken");