how about this indentation

cats

vr.addListMember({
  'session_id'  => sid,
  'list_member' => {
    'list_id'     => lid,
    'member_data' =>  [ 
      {
        'name'  => 'email_address',
        'value' => 'email@example.com'
      },
      {
         'name'  => 'first_name',
         'value' => 'Peter'
      },
      {
         'name' => 'last_name',
         'value' => 'Parker'
      }
    ]
  }
})