code: public AstNode getChildforNameAndType( AstNode astNode,
                                             String name,
                                             String nodeType ) {
          CheckArg.isNotNull(astNode, "astNode");
          CheckArg.isNotNull(name, "name");
          CheckArg.isNotNull(nodeType, "nodeType");
  
          for (AstNode child : astNode.getChildren()) {
              if (hasMixinType(child, nodeType)) {
                  if (name.equalsIgnoreCase(child.getName())) {
                      return child;
                  }
              }
          }
          return null;
      }
docs: Utility method to obtain a {@link AstNode} child of a parent {@link AstNode} with the given string name and node type.
  
  @param astNode the parent node; may not be null
  @param name the name property of the node; may not be null
  @param nodeType the type property of the target child node; may not be null
  @return the matched child (may be null)