code: function install(formulas) {
    'use strict';
  
    // Install each formula in formulas.
    let execResults = _.map(formulas, formula => installFormula(
      formula.name,
      formula.options,
      formula.isCask
    ));
  
    return execResults;
  }
docs: @description Installs a collection of formulas.
  
  @param {object[]} formulas - A collection of formula objects.
  
  @return {object[]} A collection of return objects from shelljs.exec().