This is how I write code (at least in Python). Almost every source file I work with, prior to check in, has

import pdb

at the top and

pdb.set_trace()

somewhere in the body of a function. I oftentimes develop by writing the start of a function, getting stuck/unsure of how to write the next step, and running the unfinished code and dropping into the REPL to experiment. In compiled languages, I miss this workflow and replicate it poorly with println "debugging" (is there a name for this? prinln-driven development?)

(to clarify, I am not the original author of this blog post, but the message resonates with me)