@mixin transform($property: none)
  // none | <transform-function>
  @include prefixer(transform, $property, webkit moz ms o spec)

@mixin placeholder
  $placeholders: ":-webkit-input" ":-moz" "-moz" "-ms-input"
  @each $placeholder in $placeholders
    &:#{$placeholder}-placeholder
      @content

@mixin appearance($value)
  @include prefixer(appearance, $value, webkit moz ms o spec)

@mixin animation-name($value)
  @include prefixer(animation-name, $value, webkit)
@mixin animation-duration($value)
  @include prefixer(animation-duration, $value, webkit)
@mixin animation-iteration-count($value)
  @include prefixer(animation-iteration-count, $value, webkit)

@mixin flex-direction($value: row)

  // Alt values.
  $value-2009: $value
  $value-2011: $value
  $direction: "normal"

  @if $value == row
    $value-2009: horizontal


  @elseif $value == "row-reverse"
    $value-2009: horizontal
    $direction: reverse


  @elseif $value == column
    $value-2009: vertical


  @elseif $value == "column-reverse"
    $value-2009: vertical
    $direction: reverse


  // 2009
  @include prefixer(box-orient, $value-2009, webkit moz spec)
  @if $direction == "reverse"
    @include prefixer(box-direction, $direction, webkit moz spec)

  // 2012
  @include prefixer(flex-direction, $value, webkit moz spec)

  // 2011 (IE 10)
  -ms-flex-direction: $value