def multiFind(string,substring):
    """Return a list if integers indicating where the substring begins in the string.
    Substrings are not allowed to overlap themselves:
        multifind('pppp','pp') = [0,2]
    If there are no matches, return []
    """
    start = 0
    indices = []
    while True:
        start = string.find(substring,start)
        if start == -1:
            return indices
        indices.append(start)
        start += len(substring)