Find an autonomous differential equation with all of the following properties:

• equilibrium solutions at $y = 0$ and $y = 4$,
  
  
• $y^{\,\prime} > 0$ for $0 < y < 4$, and
  
  
• $y^{\,\prime} < 0$ for $-\infty < y < 0$ and $4 < y < \infty$.

$\displaystyle \frac{dy}{dt} =$ help (formulas)