Rust Taskbook Level 7.5

Given a variable with a string. Check that this string is a number, i.e. consists only of digits.

Given a variable with a string, check that this string is a fraction.

Make a function that takes an array of numbers as a parameter and returns the second largest number.

Make a function that takes two numbers as parameters and returns an array filled with integers from the minimum parameter to the maximum.

Make a function that will fill an array with random Latin letters.

Make a function that will return the sum of the first N Fibonacci numbers.