def <<(clause)
      new_clauses = @clauses.dup
      new_clauses.delete clause
      self.class.new(attributes) { new_clauses + [clause] }
    end
def <<(clause)
      new_clauses = @clauses.dup
      new_clauses.delete clause
      self.class.new(attributes) { new_clauses + [clause] }
    end
@!method <<(clause)
 Returns a new statement where the clause is added

 @param [QueryBuilder::Clause] clause

 @return [QueryBuilder::Statement]