Merge Sort

def mergeLists(lista,listb):
    listc = []
    #loop through lists and add smalledt element to sorted list until one is empty
    while lista != [] and listb != []:
        if lista[0] <= listb[0]:
            listc.append(lista.pop(0))
        else:
            listc.append(listb.pop(0))
    if len(lista) >= 1:
        listc += lista
    else:
        listc += listb
    return listc

def mergeSort(listc):
    if len(listc) <= 1:
        return listc
    else:
        middle = int(len(listc)/2)
        lista = mergeSort(listc[:middle])
        listb = mergeSort(listc[middle:])
        print(middle,lista,listb)
    return mergeLists(lista,listb)


lista = ['E','I','J','H','G','F','D','B','C','A']
print(mergeSort(lista))