def col_to_dt(df,col_name,set_format = None,infer_format = True, dest = False):
    """ Coerces a column in a DataFrame to datetime
    Parameters:
    df - DataFrame
        DataFrame to operate on
    col_name - string
        Name of column to coerce
    dest - bool, default False
        Whether to apply the result to the DataFrame or return it.
        True is apply, False is return.
    """
    new_col = _pd.to_datetime(df[col_name],errors = 'coerce',
                                    format = set_format,infer_datetime_format = infer_format)
    if dest:
        set_col(df,col_name,new_col)
    else:
        return new_col