code: function checkIdent(i) {
    const start = i;
  
    if (i >= tokensLength) return 0;
  
    if (tokens[i].type === TokenType.HyphenMinus) i++;
  
    if (tokens[i].type === TokenType.LowLine ||
        tokens[i].type === TokenType.Identifier) i++;
    else return 0;
  
    for (; i < tokensLength; i++) {
      if (tokens[i].type !== TokenType.HyphenMinus &&
          tokens[i].type !== TokenType.LowLine &&
          tokens[i].type !== TokenType.Identifier &&
          tokens[i].type !== TokenType.DecimalNumber) break;
    }
  
    tokens[start].ident_last = i - 1;
  
    return i - start;
  }
docs: Check if token is part of an identifier
  @param {Number} i Token's index number
  @returns {Number} Length of the identifier