code: func (s String) ConditionalHas(conditionFunc func(source, item string) bool, item string) bool {
  	for source := range s {
  		if conditionFunc(source, item) {
  			return true
  		}
  	}
  	return false
  }
docs: // ConditionalHas returns true if and only if there is any item 'source'
  // in the set that satisfies the conditionFunc wrt 'item'.