"Write a function called doubles that takes a list of numbers as input and returns a list with the indices (positions) of elements in the original list that are the exact double of their predecessor. If there are no such elements the function returns an empty list." (PYTHON)

Example: myList = [1,2,3,6,8,4,8,1.2,2,3.1,6.2] then doubles(myList) would return [1,3,6,10]

Really confused and have no idea where to start. Thanks for the help