Remove consecutive empty lines from a piece of text

RemoveConsecutiveEmptyLines.ts

import mapAccum from "ramda/src/mapAccum";

const removeConsecutiveEmptyLines = (val: string): string =>
  mapAccum(
    (previous: null | string, current: string) => {
      return [current, previous === "" && current === "" ? null : current];
    },
    null,
    val.split("\n")
  )[1]
    .filter((val: string | null) => val !== null)
    .join("\n");