Add `pub` before the function name
Example: `pub fn my_function() {}`
For methods inside an `impl`, add `pub` before the method name
Example: `impl MyType { pub fn my_method(&self) {} }`
Make the containing module public if needed
Example: `pub mod my_module { pub fn my_function() {} }`
Make the containing struct fields public if needed
Example: `pub struct MyStruct { pub field: i32 }`
Use `pub(crate)` to make it visible within the current crate
Use `pub(super)` to make it visible to the parent module
Use `pub(in path::to::module)` to restrict visibility to a specific module path