Please write a canvas.c file in C unit that passes all $6$ tests in canvastest.c while using the function signatures in canvas.h

canvas.h:

#ifndef CANVAS

#define CANVAS

#include $"../$tuple$/$tuple$.$h$"$

$/*$ canvas related API $*/$

typedef struct canvas $\{$

unsigned int channels;

unsigned int width;

unsigned int height;

unsigned int$*$ pixels;

$\}$ Canvas;

Canvas canvas$($unsigned int, unsigned int$)$;

Canvas write$\_$pixel$($Canvas$,$ unsigned int, unsigned int, Color$)$;

Color pixel$\_$at$($Canvas$,$ unsigned int, unsigned int$)$;

char$*$ canvas$\_$to$\_$ppm$($Canvas$)$;

#endif