quoted_include_columns_for_index

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 895
        def quoted_include_columns_for_index(column_names) # :nodoc:
          return quote_column_name(column_names) if column_names.is_a?(Symbol)

          quoted_columns = column_names.each_with_object({}) do |name, result|
            result[name.to_sym] = quote_column_name(name).dup
          end
          add_options_for_index_columns(quoted_columns).values.join(", ")
        end