def add_index(columns, index_name = nil)
      options = { name: index_name } if index_name
      migration.add_index(table_name, columns, options || {})
    end
def add_index(columns, index_name = nil)
      options = { name: index_name } if index_name
      migration.add_index(table_name, columns, options || {})
    end
Adds an index in the specified columns through ActiveRecord. Note you
 can provide a name as well

 @param columns [Array<String>, Array<Symbol>, String, Symbol]
 @param index_name [String]