[demo request] Is there any demo for using query-syntax #Capturing Nodes?

[liaodalin19903]

Hi,
I am read the document of tree-sitter:
query-syntax #Capturing Nodes

there use @ to capture the nodes:

 (assignment_expression
  left: (identifier) @the-function-name
  right: (function))

but I don't find a place of use the captured node name(in there @the-function-name) ,
is there any demo for using this function?