Downward Rightarrow for natural transformation, tikzcd

Question

I am pretty sure this is out there on this site, but I did not find it after searching.

How to draw a downward

\Rightarrow

in a commutative tikzcddiagram?

Answer 1

Seems like many users do not really understand your second request. Even though my crystal ball got stolen, I am guessing that you are looking for \arrow[d,Rightarrow] and \arrow[d,dash].

\documentclass[fleqn]{article} 
\usepackage{tikz-cd} 
\begin{document} 
\[
\begin{tikzcd} X \arrow[d,Rightarrow] & A \arrow[d,dash]\\ 
Y & B
\end{tikzcd} 
\]
\end{document}