code: function loadFields(list, callback) {
    list.forEach(loadMethods)
  
    function loadMethods(field) {
      var module = require('./fields/' + field + '.js')
        , methods
  
      if (typeof module === 'function' || typeof module === 'string') {
        methods = {}
        methods[field] = module
      }
      else {
        methods = module
      }
  
      callback(methods)
    }
  }
docs: Load fields setters
  
  @param {string[]} list List of fields
  @param {function} callback Accepts arguments: (methods)