they are composed of instructions. Those instructions live in memory. in the
assembly program, these are labeled. The label is an address, just like a label
for a variable. In a higher level language, you typically wouldnt allow the user
to just pass the raw function somewhere. You have to get its address. C makes it
so that the bare name refers to label (which is inconsistent with variable names
which give you the value). I believe rust has actual separate function types in
this way. iirc each function in rust you define is its own unique type since
they will all have different sizes in memory.