nice radix conversion from int to string

counting matches of '1' is simple, and could easily scale to higher radixes such as octal
could easily be extended to match multiple digits, such as .count('137')

range traversal is clear

accumulator function sum() over a list is also a nice aggregate function

Well, having to figure it out in native code on your own makes it a great kata on dynamic programming.

How does this have anything to do with math?

that is a smart solve ,, i like it , i know that is don't best practice and there was more solutions is more readable than it's but this is a new practice and a new way for the solution for me, so i like it.
i know my english language is bad :)

First time I notice that if R and or G if greater than B we get yellow :D :D :D
But overall nice one ;)

C# Translation

Approved

python new test frameworks

it doesn't work for None

this kata should enforce the use of a regexp by having the user provide it as variable, as should be done in all regexp katas.

dictionary lover ;-)