Reversing a sting codeacademy exercise (python)

I need to reverse a string without using the reverse function or [::-1].

My code so far is:

def reverse(text):
        if len(text) == 1:
        return text
    else:
        x= []
        y= ""
        for i in xrange(len(text)-1, -1, -1):
            x[len(text) - i] = text[i]
        for i in xrange(0,len(x)):
            y[i] = x[i]
        return y

The error I receive is "list assignment index out of range", although I am unsure why I am getting this. Thanks for any help.