`<= vs `==

Just to expand a bit, ` is _not_ a syntax to declare an lfun. It's just a syntax to create certain identifiers not conforming to the usual letters-and-numbers form. Kind of like the | character in Common LISP. You can use such identifiers anywhere, for example

int `< = 3;

is a correct declaration of a local variable.

A method is treated like an lfun iff its name matches one of the existing lfun names. Not all lfuns have names using the ` form (for example "_indices" and "_values" do not), and not all names on the ` form are lfuns (examples include your "`<=", and things like "```!" (no lfun currently has a name with more than two ` at the beginning)).