This my implementation of the Merge Sorting Algorithm:

def merge(series1, series2):
    output = []
    while series1 != [] or series2 != []:
        if series1 == []:
            output.append(series2[0])
            series2.pop(0)
            continue
        if series2 == []:
            output.append(series1[0])
            series1.pop(0)
            continue
        last1 = series1[0]
        last2 = series2[0]
        if last1 <= last2:
            series1.pop(0)
            output.append(last1)
            continue
        if last2 < last1:
            series2.pop(0)
            output.append(last2)
            continue
    return output

def is_even(x):
    if x%2 == 0:
        return True
    return False

def merge_sort(series):
    iseries = []
    for i in series:
        iseries.append([i])
    while len(iseries) > 1:
        output = []
        length = len(iseries)
        if not is_even(length):
            length -= 1
            for i in range(0, (length-1), 2):
                a = iseries[i]
                b = iseries[i+1]
                output.append(merge(a, b))
            output.append(iseries[-1])
        else:
            for i in range(0, (length-1), 2):
                a = iseries[i]
                b = iseries[i+1]
                output.append(merge(a, b))
        iseries = []
        iseries += output
    return iseries[0]

Basically it splits the items in the initial series into lists of one item(series to iseries). Then I merge the items two-by-two appending the new items to another list(output), and set the main series equals to (output). I do this until it's 1 item only and return the 1st item(return iseries[0]).