code: function size (o) {
                      switch(true) {
                          case typeof o === 'function':
                              return 1;
  
                          case typeof o === 'number':
                              return o.toString().length;
  
                          case o instanceof Array:
                          case typeof o === 'string':
                              return o.length;
  
                          case libs.object.isArguments(o) && typeof o.length !== 'undefined':
                              return o.length;
  
                          case o && typeof o === 'object':
                              return Object.keys(o).length;
  
                          default:
                              return 0;
                      }
                  }
docs: Returns the 'size' or 'length' of an object.
  <ul>
  <li> String   -> The string's length  </li>
  <li> Number   -> The number of digits </li>
  <li> Object   -> The number of keys   </li>
  <li> Array    -> The number of items  </li>
  <li> Function -> 1                    </li>
  </ul>
  @param {Object} o The object to operate on.
  @returns {Number} The number of items within the object.
  @function