Write a C program that includes the definitions of the following functions: a) is_lower(..) : is it a lower-case letter b) is_upper(..) : is it an upper-case letter c) is_alpha(..) : is it an alphabet d) is_digit(..) : is it a digit e) is_alphanum(..) is it an alphanumeric symbol f) to_lower(..) : converts to a lower-case letter if it is upper g) to_upper(..) : converts to an upper-case letter if it is lower h) distance(..) : calculates the distance between two discrete points in a Cartesian coordinate system as below d = = /02 – Y1)² + (x2 – x1)² i) is_prime(..) : finds out whether the number is prime or not

Invoking a function that takes many arguments, the order in which parameters are supplied is crucial.

Write a function named contains-double in Scheme that takes a list as input and returns true if an item every appears twice in a row. You may assume the list is flat (i.e., no nested lists).