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Tell whether each of the following are recursive, RE-but-not-recursive, or non-RE.

  1. The set of all $TM$ codes for $TM's$ that halt on every input.
  2. The set of all $TM$ codes for $TM’s$ that halt on no input.
  3. The set of all $TM$ codes for $TM's$ that halt on at least one input.
  4. The set of all $TM$ codes for $TM's$ that fail to halt on at least one input.  
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