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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 try_get_column(column_name, node, context):
 """Attempt to get a column by name from the selectable. Args: column_name: str, name of the column to retrieve. node: SqlNode, the node the column is being retrieved for. context: CompilationContext, compilation specific metadata. Returns: Optional[column], the SQLAlchemy column if found, None otherwise. """

    selectable = get_node_selectable(node, context)
    if not hasattr(selectable, 'c'):
        raise AssertionError(
            u'Selectable "{}" does not have a column collection. Context is {}.'.format(
                selectable, context))
    return selectable.c.get(column_name, None)