comefrom: <doocs>1228.Missing Number In Arithmetic Progression_1.py
code: def missingNumber( arr: List[int]) -> int:
      n = len(arr)
      d = (arr[-1] - arr[0]) // n
      for i in range(1, n):
          if arr[i] != arr[i - 1] + d:
              return arr[i - 1] + d
      return arr[0]
masked: def sample_funcname ( var_0 : List [ int ] ) -> int :
      var_4 = len ( var_0 )
      var_7 = ( var_0 [ - 1 ] - var_0 [ 0 ] ) // var_4
      for var_9 in range ( 1 , var_4 ) :
          if var_0 [ var_9 ] != var_0 [ var_9 - 1 ] + var_7 :
              return var_0 [ var_9 - 1 ] + var_7
      return var_0 [ 0 ]
  