Conditional for File existing or not

[atltt]

Refered from here: https://powerusers.microsoft.com/t5/Building-Flows/File-Conditionals-Based-on-existing/m-p/235882#M2...

When an user starts a flow they should have the option to submit a file alongside it. Since this field can be optional, there should be a conditional to see if a file was submitted or not. Ideally, I shouldn't need to bother witha conditional and the Flow should recognize there is not a file and not break when I try to run it without a file. 

Thanks!