code: func Minimal(x interface{}) (resolved []ast.Ref, err error) {
  	rawResolved, err := All(x)
  	if err != nil {
  		return nil, err
  	}
  
  	if len(rawResolved) == 0 {
  		return nil, nil
  	}
  
  	return filter(rawResolved, func(a, b ast.Ref) bool {
  		return b.HasPrefix(a)
  	}), nil
  }
docs: // Minimal returns the list of data ast.Refs that the given AST element depends on.
  // If an AST element depends on a ast.Ref that is a prefix of another dependency, the
  // ast.Ref that is the prefix of the other will be the only one in the returned list.
  //
  // As an example, if an element depends on data.x and data.x.y, only data.x will
  // be in the returned list.