Function builtin_setdiff 

fn builtin_setdiff(
    args: &[RValue],
    _: &[(String, RValue)],
) -> Result<RValue, RError>

Set difference: elements in x that are not in y.

Works on character, integer, and double vectors. For numeric inputs, returns a numeric vector; for character inputs, returns a character vector.

@param x vector @param y vector @return vector of elements in x but not y