def column(name, definition)
      @column ||= if definition.is_a?(Symbol)
                    ColumnWithType.new(name, definition)
                  else
                    ColumnWithSql.new(name, definition)
                  end
    end
def column(name, definition)
      @column ||= if definition.is_a?(Symbol)
                    ColumnWithType.new(name, definition)
                  else
                    ColumnWithSql.new(name, definition)
                  end
    end
Returns the instance of ActiveRecord column with the given name and
 definition

 @param name [String, Symbol]
 @param definition [String]