code: def _find_form_xobject_images(pdf, container, contentsinfo):
      
      if '/Resources' not in container:
          return
      resources = container['/Resources']
      if '/XObject' not in resources:
          return
      xobjs = resources['/XObject'].as_dict()
      for xobj in xobjs:
          candidate = xobjs[xobj]
          if candidate['/Subtype'] != '/Form':
              continue
  
          form_xobject = candidate
          for settings in contentsinfo.xobject_settings:
              if settings.name != xobj:
                  continue
  
              # Find images once for each time this Form XObject is drawn.
              # This could be optimized to cache the multiple drawing events
              # but in practice both Form XObjects and multiple drawing of the
              # same object are both very rare.
              ctm_shorthand = settings.shorthand
              yield from _process_content_streams(
                  pdf=pdf, container=form_xobject, shorthand=ctm_shorthand
              )
docs: Find any images that are in Form XObjects in the container
  
      The container may be a page, or a parent Form XObject.