format.Node
// Node formats node in canonical gofmt style and writes the result to dst.
//
// The node type must be *ast.File, *printer.CommentedNode, []ast.Decl,
// []ast.Stmt, or assignment-compatible to ast.Expr, ast.Decl, ast.Spec,
// or ast.Stmt. Node does not modify node. Imports are not sorted for
// nodes representing partial source files (for instance, if the node is
// not an *ast.File or a *printer.CommentedNode not wrapping an *ast.File).
//
// The function may return early (before the entire result is written)
// and return a formatting error, for instance due to an incorrect AST.
func Node(dst io.Writer, fset *token.FileSet, node any) error
format.Source
// Source formats src in canonical gofmt style and returns the result
// or an (I/O or syntax) error. src is expected to be a syntactically
// correct Go source file, or a list of Go declarations or statements.
//
// If src is a partial source file, the leading and trailing space of src
// is applied to the result (such that it has the same leading and trailing
// space as src), and the result is indented by the same amount as the first
// line of src containing code. Imports are not sorted for partial source files.
func Source(src []byte) ([]byte, error)