code: public function setString(string $key, $value, string $ignoredDefaultValue = null)
      {
          $this->set($key, (string) $value, $ignoredDefaultValue);
          return $this;
      }
docs: Sets a string value to the builder.
  @param string $key
  @param mixed $value
  @param string|null $ignoredDefaultValue
  @return $this