def variant_cv_diagnosise(value)
      # try an NOS suffix variation
      variation = value =~ /, NOS$/ ? value[0...-', NOS'.length] : value + ', NOS'
      SpecimenCollectionGroup.diagnosis_controlled_value(variation) rescue nil
    end
def variant_cv_diagnosise(value)
      # try an NOS suffix variation
      variation = value =~ /, NOS$/ ? value[0...-', NOS'.length] : value + ', NOS'
      SpecimenCollectionGroup.diagnosis_controlled_value(variation) rescue nil
    end
Returns the tissue site which adds the 'NOS' suffix to a value without one or removes
 'NOS' from a value with the suffix.

 @return [String, nil] a supported variant of the input value, or nil if none
 @raise (see ControlledValueFinder#controlled_value)