    /*
     *  call-seq:
     *     token.pos_inc = pos_inc -> integer
     *
     *  Set the position increment.  This determines the position of this token
     *  relative to the previous Token in a TokenStream, used in phrase
     *  searching.
     *
     *  The default value is 1.
     *
     *  Some common uses for this are:
     *
     *  * Set it to zero to put multiple terms in the same position.  This is
     *    useful if, e.g., a word has multiple stems.  Searches for phrases
     *    including either stem will match.  In this case, all but the first
     *    stem's increment should be set to zero: the increment of the first
     *    instance should be one.  Repeating a token with an increment of zero
     *    can also be used to boost the scores of matches on that token.
     *
     *  * Set it to values greater than one to inhibit exact phrase matches.
     *    If, for example, one does not want phrases to match across removed
     *    stop words, then one could build a stop word filter that removes stop
     *    words and also sets the increment to the number of stop words removed
     *    before each non-stop word.  Then exact phrase queries will only match
     *    when the terms occur with no intervening stop words.
     *
     */
    static VALUE
    frb_token_set_pos_inc(VALUE self, VALUE rpos_inc)
    {
        RToken *token;
        GET_TK(token, self);
        token->pos_inc = FIX2INT(rpos_inc);
        return rpos_inc;
    }