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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 _create_function(name, doc=""):
 """Create a PySpark function by its name"""

    def _(col):
        sc = SparkContext._active_spark_context
        jc = getattr(sc._jvm.functions, name)(col._jc if isinstance(col, Column) else col)
        return Column(jc)
    _.__name__ = name
    _.__doc__ = doc
    return _