def find_repeat(source, elmt): 
    """Helper function, find index of repreat elements in source."""
    elmt_index = []
    s_index = 0;e_index = len(source)
    while(s_index < e_index):
        try:
            temp = source.index(elmt, s_index, e_index)
            elmt_index.append(temp)
            s_index = temp + 1
        except ValueError:
            break
            
    return elmt_index