code: def from_mapping(self, *mapping, **kwargs):
          
          mappings = []
          if len(mapping) == 1:
              if hasattr(mapping[0], 'items'):
                  mappings.append(mapping[0].items())
              else:
                  mappings.append(mapping[0])
          elif len(mapping) > 1:
              raise TypeError('expected at most 1 positional argument, got %d' % len(mapping))
  
          mappings.append(kwargs.items())
          for mapping in mappings:
              for key, value in mapping:
                  if key.isupper():
                      self[key] = value
          return True
docs: Updates the config like :meth:`update` ignoring items with non-upper
          keys.