code: def set_vars(self, *args, **kwargs):
          
          kwargs.update(dict(*args))
          old_values = {vname: self.input.get(vname) for vname in kwargs}
          self.input.set_vars(**kwargs)
          if kwargs or old_values:
              self.history.info("Setting input variables: %s" % str(kwargs))
              self.history.info("Old values: %s" % str(old_values))
  
          return old_values
docs: Set the values of the ABINIT variables in the input file. Return dict with old values.