code: function installFormula(formula, options, isCask) {
    'use strict';
    let installCmd = isCask ? 'brew cask install' : 'brew install';
    let optionsString = options ? options.join(' ') : '';
    let cmd = `${installCmd} ${formula} ${optionsString}`;
  
    let execResult = shell.exec(cmd);
  
    return execResult;
  }
docs: @description Installs a homebrew formula.
  
  @param {string} formula - The formula you would like to install.
  @param {string[]} options - An array of options for the formula,
  possibly empty.
  @param {boolean} isCask - Is the formula you're installing a cask?
  
  @return {object} The return object of shelljs.exec().