What three things does a flashing green light at an intersection where you are permitted to turn both left and right mean?

• You may turn to the left if the way is clear
  Explanation:

  "You may turn to the left if the way is clear"
• You may turn to the right if the way is clear
  Explanation:

  "You may turn to the left if the way is clear"
• You may proceed straight through if the way is clear
  Explanation:

  "You may turn to the left if the way is clear"
• You must stop