Simple python stack class with a sorting method

pystack.py

class Stack:
    def __init__(self):
        self.data = []

    def push(self, item):
        self.data.append(item)

    def pop(self):
        return self.data.pop()

    def show(self):
        return self.data
    
    def selectionSort(self):
        # mutates the original stack, sorts ASC, only handles numerics
        # could probably use some error handling
        # adapted from interactivepython.org
        for fillslot in range(len(self.data)-1,0,-1):
            positionOfMax=0
            for location in range(1,fillslot+1):
                if self.data[location]>self.data[positionOfMax]:
                    positionOfMax = location
     
            temp = self.data[fillslot]
            self.data[fillslot] = self.data[positionOfMax]
            self.data[positionOfMax] = temp