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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def getAllCellsInColumns(columns, cellsPerColumn):
 """ Calculate all cell indices in the specified columns. @param columns (numpy array) @param cellsPerColumn (int) @return (numpy array) All cells within the specified columns. The cells are in the same order as the provided columns, so they're sorted if the columns are sorted. """


  # Add
  #   [[beginningOfColumn0],
  #    [beginningOfColumn1],
  #     ...]
  # to
  #   [0, 1, 2, ..., cellsPerColumn - 1]
  # to get
  #   [beginningOfColumn0 + 0, beginningOfColumn0 + 1, ...
  #    beginningOfColumn1 + 0, ...
  #    ...]
  # then flatten it.
  return ((columns * cellsPerColumn).reshape((-1, 1)) +
          np.arange(cellsPerColumn, dtype="uint32")).flatten()