class Arel::InsertManager

def insert(fields)
  return if fields.empty?
  if String === fields
    @ast.values = Nodes::SqlLiteral.new(fields)
  else
    @ast.relation ||= fields.first.first.relation
    values = []
    fields.each do |column, value|
      @ast.columns << column
      values << value
    end
    @ast.values = create_values(values)
  end
  self
end