def __init__(<EOL>self, column_name, name, aggregate_func=aggregate_count, aggregate_col="<STR_LIT>"<EOL>):
self.column_name = column_name<EOL>self.name = name<EOL>self.aggregate_func = aggregate_func<EOL>self.aggregate_col = aggregate_col<EOL>
Constructor.

:param column_name:
    Model field name
:param name:
    The group by name