Missing visible-** and hidden-** in Bootstrap v4

_visibility_classes.scss

// Restore Bootstrap 4 alpha "hidden" utility classes.
@each $bp in map-keys($grid-breakpoints) {
  .hidden-#{$bp}-up {
    @include media-breakpoint-up($bp) {
      display: none !important;
    }
  }
  .hidden-#{$bp}-down {
    @include media-breakpoint-down($bp) {
      display: none !important;
    }
  }
  .hidden-#{$bp}-only{
    @include media-breakpoint-only($bp) {
      display:none !important;
    }
  }
}

bootstrap4_visibility_classes.md

Missing visible-** and hidden-** in Bootstrap v4

The hidden-* and visible-* classes no longer exist in Bootstrap 4 Beta. If you want to hide an element on specific tiers or breakpoints in Bootstrap 4, use the d-* display classes accordingly. Remember xs is the default (implied) breakpoint, unless overridden by a larger breakpoint.

Old Class	New Class
hidden-xs-down	d-none d-sm-block
hidden-sm-down	d-none d-md-block
hidden-md-down	d-none d-lg-block
hidden-lg-down	d-none d-xl-block
hidden-xl-down	d-none (same as hidden)
hidden-xs-up	d-none (same as hidden)
hidden-sm-up	d-sm-none
hidden-md-up	d-md-none
hidden-lg-up	d-lg-none
hidden-xl-up	d-xl-none
hidden-xs (only)	d-none d-sm-block (same as hidden-xs-down)
hidden-sm (only)	d-block d-sm-none d-md-block
hidden-md (only)	d-block d-md-none d-lg-block
hidden-lg (only)	d-block d-lg-none d-xl-block
hidden-xl (only)	d-block d-xl-none
visible-xs (only)	d-block d-sm-none
visible-sm (only)	d-none d-sm-block d-md-none
visible-md (only)	d-none d-md-block d-lg-none
visible-lg (only)	d-none d-lg-block d-xl-none
visible-xl (only)	d-none d-xl-block