add_loc_to_function

module.exports = function ({types: t}) {
  return {
//    name: "ast-transform", // not required
    visitor: {
      Identifier(path, state) {
        //path.node.name = path.node.name.split('').reverse().join('');
        //console.log('test', path.node)
        //path.node.name = path.node.name + '_' + loc.start.line + '_' + loc.start.column
      },
      FunctionDeclaration: {
          exit(path, state) {
            const filename = state.file.opts.filename;
            const loc = path.node.loc
            const body = path.get('body')
            body.unshiftContainer('body',
                t.expressionStatement(
                    t.callExpression(
                        t.memberExpression(t.identifier('console'), t.identifier('log')),
                        [t.stringLiteral(filename), t.stringLiteral(path.node.id.name), t.identifier('loc')]
                    )
                )
            );
            body.unshiftContainer('body', 
                t.variableDeclaration('const', [
                    t.variableDeclarator(t.identifier('loc'), t.identifier(JSON.stringify(loc)))
                ])
            );
          }
      }
    }
  };
}