function directedEdgeToBoundary(edgeIndex, formatAsGeoJson) {
    const cellBoundary = C._malloc(SZ_CELLBOUNDARY);
    const [lower, upper] = h3IndexToSplitLong(edgeIndex);
    try {
        throwIfError(H3.directedEdgeToBoundary(lower, upper, cellBoundary));
        return readCellBoundary(cellBoundary, formatAsGeoJson);
    } finally {
        C._free(cellBoundary);
    }
}
Get the vertices of a given edge as an array of [lat, lng] points. Note that for edges that
cross the edge of an icosahedron face, this may return 3 coordinates.
@static
@param  {H3IndexInput} edgeIndex        H3 index of the edge
@param {boolean} [formatAsGeoJson] Whether to provide GeoJSON output: [lng, lat]
@return {CoordPair[]}              Array of geo coordinate pairs
@throws {H3Error}                  If the input is invalid