title: Element-wise operation on tensorflow tensor
body: <p>I'm new to tensorflow, and need to do something that in any other context wouldn't be that hard.</p>
  
  <p>I need to take a tensor with shape (?, 224, 224, 3) and apply an operation to each element, leaving the size in tact. I've tried tf.map_fn(myFunc, data), but it seems like what gets passed in to myFunc is a subset of the original tensor.</p>
  
  <p>Is there any easy way to just say "do this operation to everything in the tensor"?</p>