code: def iter(self, obj=None):
          'Iterate through all keys considering context of obj. If obj is None, uses the context of the top sheet.'
          if obj is None and vd:
              obj = vd.sheet
  
          for o in self._mappings(obj):
              for k in self.keys():
                  for o2 in self[k]:
                      if o == o2:
                          yield (k, o), self[k][o2f iter(self, obj=None):
          'Iterate through all keys considering context of obj. If obj is None, uses the context of the top sheet.'
          if obj is None and vd:
              obj = vd.sheet
  
          for o in self._mappings(obj):
              for k in self.keys():
                  for o2 in self[k]:
                      if o == o2:
                          yield (k, o), self[k][o2]
docs: Iterate through all keys considering context of obj. If obj is None, uses the context of the top sheet.