code: def contains_variables_from_set(expression, variables):
      
      if hasattr(expression, 'variable_name') and expression.variable_name in variables:
          return True
      if isinstance(expression, Operation):
          return any(contains_variables_from_set(o, variables) for o in op_iter(expression))
      return False
docs: Returns True iff the expression contains any of the variables from the given set.