define a function that takes a string as an input and finds which letter exists how many times in the given string, and then create another function that uses the output dictionary from the first function and creates a new dictionary that maps from frequencies to letters. a sample for the second one is$,$ Sample input$/$Output:

$$ res $=$ hist A$($kara murat kim$))$

$$ print$($hist B$($res$))$

$\{1$: $[$u$,$t$,$i$],2$: $[,$r$,$k$,$m$],3$: $[$a$]\}$