I> descriptive_function(rivers, ‘v’, 8)[1] 243908.4> descriptive_function(rivers, ‘z’, 8)n this exercise, you will work with rivers data. The data pertain to the length of major North American rivers, and it is built-in data in R. You can access the data by typing:> riversYour task is to build a function that returns descriptive statistics for different inputs. The function is named descriptive_function and has three arguments (i.e., another name of inputs).descriptive_function(list, char, num)The requirements of the function are as follows:· The function has three arguments. The first argument is a list of numbers in doubles. The second argument is a character, and the last argument is a number.· If char is ‘m ’, the function prints the arithmetic mean of the list.· If char is ‘v’, the function prints the variance of the list.· If char is ‘s’, the function prints the standard deviation of the list.· If char is ‘z’, the function prints the z-score of num with respect to the list.· You can use built-in R functions including mean(), var() and sd().Sample test cases:> descriptive_function(rivers, ‘m’, 7)[1] 591.1844> descriptive_function(rivers, ‘m’)[1] 591.1844> descriptive_function(rivers, ‘s’)[1] 493.8708[1] -1.180844
