A more efficient version of the function for computing Tetranacci numbers can be defined by following three steps: 1. Implement a function which takes a list of integers and adds the sum of the top four elements to the head of the list (e. g., in F#, 1::1::1:1::/) should become 4:-1:-1::1::1::]). 2. Implement a recursive function which accepts an integer n as input (again, assumen > 0), and returns a list of integers from 0 to n in ascending order 3. Implement a recursive function which computes the nth Tetranacci number in linear time. This function may use a linear amount of space to compute its result, but the number of recursive calls it makes must be linear in n. Your task is to follow the three steps above, in order to implement the requested function in F#