function join(array, separator) {
      return array == null ? '' : nativeJoin.call(array, separator);
    }
Converts all elements in `array` into a string separated by `separator`.

@static
@memberOf _
@since 4.0.0
@category Array
@param {Array} array The array to convert.
@param {string} [separator=','] The element separator.
@returns {string} Returns the joined string.
@example

_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'