code: public static function textarea($name, $value = '', $options = [])
      {
          $options['name'] = $name;
          $doubleEncode = ArrayHelper::remove($options, 'doubleEncode', true);
          return static::tag('textarea', static::encode($value, $doubleEncode), $options);
      }
docs: Generates a text area input.
  @param string $name the input name
  @param string $value the input value. Note that it will be encoded using [[encode()]].
  @param array $options the tag options in terms of name-value pairs. These will be rendered as
  the attributes of the resulting tag. The values will be HTML-encoded using [[encode()]].
  If a value is null, the corresponding attribute will not be rendered.
  See [[renderTagAttributes()]] for details on how attributes are being rendered.
  The following special options are recognized:
  
  - `doubleEncode`: whether to double encode HTML entities in `$value`. If `false`, HTML entities in `$value` will not
  be further encoded. This option is available since version 2.0.11.
  
  @return string the generated text area tag