How about a function called contains() for the module std.array?

[Murilo]

I needed a function that tells if an array contains the elements 
of another, as in `[1, 2, 3, 4, 5, 6].contains([6, 4])` by 
returning a `bool`. I did not find such function so I made my own 
version but I'm unable to submit a PR on GitHub since I don't 
know how to write a function using that style that I saw on 
GitHub. I imagine that maybe you guys could take my function and 
refactor it so it will be according to your rules and then add it 
to std.array. What do you think?
Here is my function:
//This function returns a bool telling if an array totally 
contains the elements of a smaller array
import std.algorithm.searching : countUntil;
import std.algorithm.sorting : sort;

bool contains(long[] a, long[] b)
{
     //first we sort both of them
     sort(a);
     sort(b);
     //now we check them using slices and return the result
     return b == a[a.countUntil(b[0]) .. a.countUntil(b[$ - 1]) + 
1];
}
/*
Example:
long[] a = [3, 9, 1, 4, 7, 6, 5, 8, 2];
long[] b = [5, 4, 6];
writeln(contains(a, b));
*/