An ascii string is made 'dank' when exactly one space is inserted between any two consecutive letters and all capital letters are replaced with lowercase ones. In this challenge I would like you to write a program that takes a string (not necessarily 'dank') as input and outputs a 'dank' version of that string.
Your program should take as input an ascii string of arbitrary length and output another ascii string.
A string is classed as dank when it contains only spaces and lowercase letters such that there is exactly one space between any two consecutive letters. To make a string dank you'll have to strip all non-alphabetical characters, replace capital letters with their lowercase counterparts, then insert spaces between all the characters.
"aesthetic" > "a e s t h e t i c" "How are you?" > "h o w a r e y o u" "drop // top" > "d r o p t o p"
Code golf so the shortest code in bytes wins.
g o o d l u c k