[Urgent] Modifying PHP's core

[Involution]

What is all dependent on PHP?

I mean lets say I removed echo from phps source code.

Then I add function my_echo() which is the exact same code basically, what all would I need to update to allow my_echo() to be implemented correctly

 

Obviously I would need to modify every one of my php scripts on my webserver to replace echo with my_echo, but is there anything else?

 

I know i could just append my_echo to phps source, or modify the echo function itself, but this is conceptually and thats not the actual process I'm looking for right now.

 

Any insight would be greatly appreciated!