code: function checkOperator(i) {
    if (i >= tokensLength) return 0;
  
    switch (tokens[i].type) {
      case TokenType.Solidus:
      case TokenType.Comma:
      case TokenType.Colon:
      case TokenType.EqualsSign:
      case TokenType.Asterisk:
        return 1;
    }
  
    return 0;
  }
docs: Check if token is an operator (`/`, `,`, `:`, `=`, `*`).
  @param {Number} i Token's index number
  @return {Number} `1` if token is an operator, otherwise `0`