code: def relabel_variables(self, mapping, inplace=True):
          
          if not inplace:
              return self.copy().relabel_variables(mapping, inplace=True)
  
          try:
              old_labels = set(mapping)
              new_labels = set(mapping.values())
          except TypeError:
              raise ValueError("mapping targets must be hashable objects")
  
          variables = self.variables
          for v in new_labels:
              if v in variables and v not in old_labels:
                  raise ValueError(('A variable cannot be relabeled "{}" without also relabeling '
                                    "the existing variable of the same name").format(v))
  
          shared = old_labels & new_labels
          if shared:
              old_to_intermediate, intermediate_to_new = resolve_label_conflict(mapping, old_labels, new_labels)
  
              self.relabel_variables(old_to_intermediate, inplace=True)
              self.relabel_variables(intermediate_to_new, inplace=True)
              return self
  
          for oldterm, bias in list(self.items()):
              newterm = frozenset((mapping.get(v, v) for v in oldterm))
  
              if newterm != oldterm:
                  self[newterm] = bias
                  del self[oldterm]
  
          return self
docs: Relabel variables of a binary polynomial as specified by mapping.
  
          Args:
              mapping (dict):
                  Dict mapping current variable labels to new ones. If an
                  incomplete mapping is provided, unmapped variables retain their
                  current labels.
  
              inplace (bool, optional, default=True):
                  If True, the binary polynomial is updated in-place; otherwise, a
                  new binary polynomial is returned.
  
          Returns:
              :class:`.BinaryPolynomial`: A binary polynomial with the variables
              relabeled. If `inplace` is set to True, returns itself.