Stand with your feet together pointing straight in front of you, and your arms open diagonally to the sides, palms up. 
Bend both knees and hips.
Turn to your left and shift weight to the left.  Cross your right wrist over your left wrist.
With your weight still on the left turn your trunk to the right .  Start shifting and turning towards your right side.  The right hand curves toward your belly button and continues to straighten out.  The left follows (or chases) the right winding up with your forearm parallel and in front of your chest.  Once you have reached the maximum of your turn to the right, start pulling with your back foot to shift your weight back.  The right forearm comes toward your forehad and the left strike straight out as if attacking an opponent's throat.
Pull with the right to shift the weight to the right and then pull with the left to complete the movement.  The arms extend in front of the body as they come around.

 

Below is a clip of Master William Ting performing Snake Attack. 
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