How to return mock data of nested calling function in jest?

Question

I have two util functions

export const functionB = (a) => {
   return a + 2
}

export const functionA = () => {
  const valueA = 5
  const valueB = functionB(valueA)

  return {
   valueA,
   valueB
  }
}

In the test, when I use FunctionA, I want to fake the return of FunctionB such that it returns my desired value instead of 7.

How am I going to do it?