in ML one line of code

Write a function lconcat of type 'a list list 'a list that takes a list of lists as input and returns the list formed by appending the input lists together in order. For example, if the input is [ [1,2], [3 5, 6] , [7] ], your function should return [ 1 , 2 , 3,4 , 5, 6, 7](There s a predefined function like this called concat, which of course you should not use.) Write a function lconcat of type 'a list list 'a list that takes a list of lists as input and returns the list formed by appending the input lists together in order. For example, if the input is [ [1,2], [3 5, 6] , [7] ], your function should return [ 1 , 2 , 3,4 , 5, 6, 7](There s a predefined function like this called concat, which of course you should not use.)