Define (i. e. write) the function (echo lst). This function doubles each top-level element of list lst. E. g., (echo '(a b c)) returns (a a b b c c). (echo '(a (b c))) returns (a a (b c) (b c)) 2. Define the function (echo-lots lst n). (echo-lots '(a (b c)) 3) returns (a a a (b c) (b c) (b c)), that is, it is like echo but it repeats each element of lst n times. 3. Define the function (echo-all lst) which is a deep version of echo. (echo-all '(a (b c)) should return (a a (b b c c)(b b c c)). 4. Define the function nth. (nth i lst) returns the ith element of lst. E. g., (nth 0 '(a b c)) returns a, and (nth 1 '(a (b c) d) returns (b c). You may assume