anchor.diff:                       +term-term-type-gt+
                        +term-term-type-ge+
                        +term-term-type-not+
  +                     +term-term-type-get-field+
                        +term-term-type-contains+
                        +term-term-type-is-empty+
                        +term-term-type-has-fields+
  
positive.code:                      +term-term-type-mul+
                       +term-term-type-div+
                       +term-term-type-mod+
                       +term-term-type-count+
                       +term-term-type-var+
                       +term-term-type-funcall+
  
negative.code:                      +term-term-type-append+
                       +term-term-type-prepend+
                       +term-term-type-difference+
                       +term-term-type-get-field+
                       +term-term-type-set-insert+
                       +term-term-type-set-intersection+
                       +term-term-type-set-union+
  