How to use the @typescript-eslint/typescript-estree.AST_NODE_TYPES.FunctionDeclaration function in @typescript-eslint/typescript-estree

ast.program.body = ast.program.body.filter((i: any) => {
    // export function a() {}
    // export interface Bang {}
    // export type Foo = string | number;
    if (
      i.type === AST_NODE_TYPES.ExportNamedDeclaration &&
      (i.declaration.type === AST_NODE_TYPES.TSTypeAliasDeclaration ||
        i.declaration.type === AST_NODE_TYPES.FunctionDeclaration ||
        i.declaration.type === AST_NODE_TYPES.TSInterfaceDeclaration)
    ) {
      return allowed.includes(i.declaration.id.name);
    }

    // export const manager = {};
    // export const {f,g: h} = {f: 4, g:5};
    if (
      i.type === AST_NODE_TYPES.ExportNamedDeclaration &&
      i.declaration.type === AST_NODE_TYPES.VariableDeclaration
    ) {
      // MUTATION!
      // eslint-disable-next-line no-param-reassign
      i.declaration.declarations = i.declaration.declarations.filter((d: any) => {
        if (d.id.type === AST_NODE_TYPES.ObjectPattern) {
          // MUTATION!

private codeFromAssignmentPattern(ast: AssignmentPattern): string {
    let str = this.codeFromAST(ast.left);
    let parent = (ast as any).__parent;
    if(!parent || (parent.type != AST_NODE_TYPES.FunctionExpression && parent.type != AST_NODE_TYPES.FunctionDeclaration)) {
       str += ' = ' + this.codeFromAST(ast.right);
    }
    return str;
  }