How to invoke the stock file browser/chooser in Android 5.1& 6.0

Question

I'm building a toolkit to carry out Root management related functions (not managing root access, but simplifying some system functions), and one of them replaces various system binaries with custom versions that the user chooses. I'm having a bit of difficulty however, in the actual invoking the stock file browser built into 5.1/6.0. I cannot seem to get it to work. Does anyone have a simple piece of example code that shows how to invoke said file browser, and load the chosen file's absolute directory into a variable? Thanks! :3