Quicksort with Python

I am totally new to python and I am trying to implement quicksort in it. Could someone please help me complete my code?

I do not know how to concatenate the three arrays and printing them.

    def sort(array=[12,4,5,6,7,3,1,15]):
        less = []
        equal = []
        greater = []

        if len(array) > 1:
            pivot = array[0]
            for x in array:
                if x < pivot:
                    less.append(x)
                if x == pivot:
                    equal.append(x)
                if x > pivot:
                    greater.append(x)
                sort(less)
                sort(pivot)
                sort(greater)
    def sort(array=[12,4,5,6,7,3,1,15]):
        less = []
        equal = []
        greater = []

        if len(array) > 1:
            pivot = array[0]
            for x in array:
                if x < pivot:
                    less.append(x)
                if x == pivot:
                    equal.append(x)
                if x > pivot:
                    greater.append(x)
            # Don't forget to return something!
            return sort(less)+equal+sort(greater)  # Just use the + operator to join lists
        # Note that you want equal ^^^^^ not pivot
        else:  # You need to hande the part at the end of the recursion - when you only have one element in your array, just return the array.
            return array

From: stackoverflow.com/q/18262306