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diff --git a/popperjs/package/lib/modifiers/offset.js.flow b/popperjs/package/lib/modifiers/offset.js.flow
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+// @flow
+import type { Placement } from '../enums';
+import type { ModifierArguments, Modifier, Rect, Offsets } from '../types';
+import getBasePlacement from '../utils/getBasePlacement';
+import { top, left, right, placements } from '../enums';
+
+// eslint-disable-next-line import/no-unused-modules
+export type OffsetsFunction = ({
+  popper: Rect,
+  reference: Rect,
+  placement: Placement,
+}) => [?number, ?number];
+
+type Offset = OffsetsFunction | [?number, ?number];
+
+// eslint-disable-next-line import/no-unused-modules
+export type Options = {
+  offset: Offset,
+};
+
+export function distanceAndSkiddingToXY(
+  placement: Placement,
+  rects: { popper: Rect, reference: Rect },
+  offset: Offset
+): Offsets {
+  const basePlacement = getBasePlacement(placement);
+  const invertDistance = [left, top].indexOf(basePlacement) >= 0 ? -1 : 1;
+
+  let [skidding, distance] =
+    typeof offset === 'function'
+      ? offset({
+          ...rects,
+          placement,
+        })
+      : offset;
+
+  skidding = skidding || 0;
+  distance = (distance || 0) * invertDistance;
+
+  return [left, right].indexOf(basePlacement) >= 0
+    ? { x: distance, y: skidding }
+    : { x: skidding, y: distance };
+}
+
+function offset({ state, options, name }: ModifierArguments<Options>) {
+  const { offset = [0, 0] } = options;
+
+  const data = placements.reduce((acc, placement) => {
+    acc[placement] = distanceAndSkiddingToXY(placement, state.rects, offset);
+    return acc;
+  }, {});
+
+  const { x, y } = data[state.placement];
+
+  if (state.modifiersData.popperOffsets != null) {
+    state.modifiersData.popperOffsets.x += x;
+    state.modifiersData.popperOffsets.y += y;
+  }
+
+  state.modifiersData[name] = data;
+}
+
+// eslint-disable-next-line import/no-unused-modules
+export type OffsetModifier = Modifier<'offset', Options>;
+export default ({
+  name: 'offset',
+  enabled: true,
+  phase: 'main',
+  requires: ['popperOffsets'],
+  fn: offset,
+}: OffsetModifier);