docs: function (inputArg) {
              var isFn = false,
                  type;
  
              if (inputArg !== null) {
                  type = typeof inputArg;
                  if ((type === 'function' || type === 'object') &&
                          ('constructor' in inputArg) &&
                          ('call' in inputArg) &&
                          ('apply' in inputArg) &&
                          ('length' in inputArg) &&
                          typeof inputArg.length === 'number') {
  
                      isFn = true;
                  }
              }
  
              return isFn;
          }