Mutating the state of immut references

[CXWorks]

Hi,

In the following code, it will register the name and value into &self, which is an immut reference. Is it a violation of Rust's reference or designed behavior?

libucl-rs/libucl/src/parser.rs

Lines 108 to 114 in 30360ec

	pub fn register_var(&self, name: String, value: String) {
	let n = CString::new(name).unwrap();
	let v = CString::new(value).unwrap();
	unsafe {
	ucl_parser_register_variable(self.parser, n.as_ptr(), v.as_ptr())
	}
	}