function getUnitAnchors(street_feature, bounding_box, unit_options) {
  let unit_anchors = [],
    unit_length = unit_options.length / 1000, //Kilometers.
    unit_buffer = unit_options.side_buffer / 1000, //Distance between units, kilometers.
    endpoint =
      street_feature.geometry.coordinates[
        street_feature.geometry.coordinates.length - 1
      ],
    start_anchor = along(street_feature, 0),
    end_anchor = along(street_feature, unit_length),
    distance_along = unit_length;

  while (end_anchor.geometry.coordinates != endpoint) {
    //Exclude proposed anchors if they're outside of the bounding box.
    (start_coord = L.A.reversedCoordinates(start_anchor.geometry.coordinates)),
      (end_coord = L.A.reversedCoordinates(end_anchor.geometry.coordinates));
    if (
      L.latLngBounds(bounding_box).contains(start_coord) &&
      L.latLngBounds(bounding_box).contains(end_coord)
    ) {
      unit_anchors.push([start_anchor, end_anchor]);
    }

    //Find next pair of anchors.
    start_anchor = along(street_feature, distance_along + unit_buffer);
    end_anchor = along(
      street_feature,
      distance_along + unit_buffer + unit_length,
    );

    distance_along += unit_buffer + unit_length;
  }

  return unit_anchors;
}
Find anchors for potential units. chors are the pairs of start
and end points along the street from which units may be constructed.
@private

@param {Feature} street_feature - A GeoJSON feature object representing a street.
@param {object} unit_options - An object containing the AgentMaps styling options for units.
@returns {Array<Array<Feature>>} - Array of pairs of points around which to anchor units along a street.