input: Write a function to detect and fix Python syntax errors in a given code snippet. If the code snippet is fixed correctly, return the corrected code. If the code cannot be fixed, return "Unable to fix".
  
  
  assert fix_syntax("def test ():\\n x = 5\\n y = 3\\n") == "def test():\\n    x = 5\\n    y = 3\\n"
  assert fix_syntax("x = 5\\n y = 3\\n z") == "x = 5\\n    y = 3\\n    try:\\n        z\\n    except NameError:\\n        print(\"NameError: Name 'z' is not defined\")"
  assert fix_syntax("def test (\\n x = 5\\n y = 3\\n") == "Unable to fix"
  assert fix_syntax("") == ""
  
output: def fix_syntax(code):
      try:
          compile(code, '<string>', 'exec')
          return code
      except SyntaxError as e:
          if "unexpected EOF" in str(e):
              return "Unable to fix"
          else:
              lines = code.split('\n')
              for i, line in enumerate(lines):
                  if line.strip() == '':
                      continue
                  if not line.startswith(' '):
                      lines[i] = '    ' + line
              return '\n'.join(lines)