findKeigo(tokens, pnt) {
    let node = keigo;
    let result;
    let currentPnt = pnt;
    let currentToken = tokens[currentPnt];
    while (currentToken && node[currentToken]) {
      node = node[currentToken];
      if (node.result) {
        result = {
          value: node.result.value,
          keigo: node.result.keigo,
          length: currentPnt - pnt + 1,
        };
      }
      currentPnt += 1;
      currentToken = tokens[currentPnt];
    }
    return result;
  }
Find a keigo chain and returns the replacement and formality level.
@param {String[]} tokens Input tokens
@param {Number} pnt Current pointer in the chain