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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 make_timestamp_columns():
 """Return two columns, created_at and updated_at, with appropriate defaults"""

    return (
        Column('created_at', DateTime, default=func.utcnow(), nullable=False),
        Column('updated_at', DateTime, default=func.utcnow(), onupdate=func.utcnow(), nullable=False),
    )