code: function sortedIndex(list, value, valueIndex) {
      if (!(list && Array.isArray(list))) {
        // Manually currying
        let args = arguments;
        return (list) => sortedIndex(list, ...args);
      }
  
      return reuseables.sorter(list, value, valueIndex);
    }
docs: Returns the lowest index number of a value if it is to be added to an array.
  @param list {Array} array that value will be added to
  @param value value to evaluate
  @param valueIndex {string} accepts either 'first' or 'last'.
  Specifies either to return the first or last index if the value is to be added to the array.
  Default is 'first'
  @returns {number}