function toString(value) {
    if (isNil(value)) {
      return null;
    }

    if (isString(value)) {
      return value;
    }

    return String(value);
  }
Get the string representation of the `value`.
Converts the `value` to string.

@ignore
@function toString
@param {*} value             The value to convert.
@return {string|null}        Returns the string representation of `value`.