I have a small function that used to produce a variety of blinking speeds and rates

Trying to make a basic timer as I have an onboard light that I can make blink at different rates. As well as perhaps a break function when the timer reaches a variable number of milliseconds.

/tmp/ccccDoxp.ltrans0.ltrans.o: In function `main':

/home/builder/.arduino15/packages/arduino/hardware/avr/1.8.4/cores/arduino/main.cpp:43: undefined reference to `setup'

collect2: error: ld returned 1 exit status

Error during build: exit status 1

^^^ Above is an error that was thrown a couple iterations ago

Post the code, using code tags.

Please post the whole of the code you are trying to upload.

You may want to read this before you proceed:-
how to get the best out of this forum

Read the forum guidelines to see how to properly post code and some good information on making a good post.
Use the IDE autoformat tool (ctrl-t or Tools, Auto format) before posting code in code tags.

Please include the entire error message. It is easy to do. There is a button (lower right of the IDE window) called "copy error message". Copy the error and paste into a post in code tags. Paraphrasing the error message leaves out important information.

Pretty sure there is an error in your code that you didn't post.