class Arel::UpdateManager

def set(values)
  case values
  when String, Nodes::BoundSqlLiteral
    @ast.values = [values]
  else
    @ast.values = values.map { |column, value|
      Nodes::Assignment.new(
        Nodes::UnqualifiedColumn.new(column),
        value
      )
    }
  end
  self
end