docs: def find_field(browser, field_type, value):
      """
      Locate an input field.
  
      :param browser: ``world.browser``
      :param string field_type: a field type (i.e. `button`)
      :param string value: an id, name or label
  
      This first looks for `value` as the id of the element, else
      the name of the element, else as a label for the element.
  
      Returns: an :class:`ElementSelector`
      """
      return find_field_by_id(browser, field_type, value) + \
          find_field_by_name(browser, field_type, value) + \
          find_field_by_label(browser, field_type, value)