code: def describe_variables(self, v):
          
          reverse_mapping = {next(iter(var.variables)): k for k, var in self.eternal_tracked_variables.items()}
          reverse_mapping.update({next(iter(var.variables)): k for k, var in self.temporal_tracked_variables.items() if k[-1] is not None})
  
          for var in v.variables:
              if var in reverse_mapping:
                  yield reverse_mapping[var]
docs: Given an AST, iterate over all the keys of all the BVS leaves in the tree which are registered.