code: function getBitDepthFunction_(original, target) {
    /** @type {!Function} */
    let func = function(x) {return x;};
    if (original != target) {
      if (["32f", "64"].includes(original)) {
        if (["32f", "64"].includes(target)) {
          func = floatToFloat_;
        } else {
          func = floatToInt_;
        }
      } else {
        if (["32f", "64"].includes(target)) {
          func = intToFloat_;
        } else {
          func = intToInt_;
        }
      }
    }
    return func;
  }
docs: Return the function to change the bit depth of a sample.
  @param {string} original The original bit depth of the data.
  One of "8" ... "53", "32f", "64"
  @param {string} target The new bit depth of the data.
  One of "8" ... "53", "32f", "64"
  @return {!Function}
  @private