matchCondition(option, textboxValue) {
    let idx = -1;
    const inputValue = this._getTextboxValueFromOption(option);
    if (typeof inputValue === 'string' && typeof textboxValue === 'string') {
      idx = inputValue.toLowerCase().indexOf(textboxValue.toLowerCase());
    }

    if (this.matchMode === 'all') {
      return idx > -1; // matches part of word
    }
    return idx === 0; // matches beginning of value
  }
When the preconfigurable `match-mode` conditions are not sufficient,
one can define a custom matching function.

@overridable
@param {LionOption} option
@param {string} textboxValue current ._inputNode value