better use an enumerate's argument for the start index

@Unnamed, @Blind4Basics: There is a Guido's article about List Comprehensions and Generator Expressions advantages - http://python-history.blogspot.com/2010/06/from-list-comprehensions-to-generator.html
But yeah, it's more about comparison between LCs and (map with lambda). Thanks for correcting me

1. It's better to use List Comprehensions instead of (map/filter) when possible
2. It's better to use Generator Expressions instead of List Comprehensions when possible

I'm sure this should be best practice

I think that we don't need to create a dictionary, a list is enough
Also no need to check if number is in the dict (easier to check if it's less or equal than 100)

a function returns None by default so you can reduce your code

I knew about that solution but I don't think that it's the best practices.
Yes, it's one-line solution but according to the pep8
we should limit all lines to a maximum of 79 characters.
As for me even if my solution has more lines it's more readable

no need to iterate over elements. If we try to check if item in our sequence it will do that for us. It item exists in sequence it will move the cursor on it