def is_standardized(table, has_time=False, verbose=True):
    """ Check if the table has the correct indices and the minimum required columns.

        Args:
            table: pandas DataFrame
                Annotation table. 
            has_time: bool
                Require time information for each annotation, i.e. start and stop times.
            verbose: bool
                If True and the table is not standardized, print a message with an example table in the standard format.

        Returns:
            res: bool
                True if the table has the standardized Ketos format. False otherwise.
    """
    required_indices = ['filename', 'annot_id']
    required_cols = ['label']
    if has_time:
        required_cols = required_cols + ['start', 'end']

    mis_cols = [x for x in required_cols if x not in table.columns.values]
    res = (table.index.names == required_indices) and (len(mis_cols) == 0)

    message = """ Your table is not in the Ketos format.

            It should have two levels of indices: filename and annot_id.
            It should also contain at least the 'label' column.
            If your annotations have time information, these should appear in the 'start' and 'end' columns

            extra columns are allowed.

            Here is a minimum example:

                                 label
            filename  annot_id                    
            file1.wav 0          2
                      1          1
                      2          2
            file2.wav 0          2
                      1          2
                      2          1


            And here is a table with time information and a few extra columns ('min_freq', 'max_freq' and 'file_time_stamp')

                                 start   end  label  min_freq  max_freq  file_time_stamp
            filename  annot_id                    
            file1.wav 0           7.0   8.1      2    180.6     294.3    2019-02-24 13:15:00
                      1           8.5  12.5      1    174.2     258.7    2019-02-24 13:15:00
                      2          13.1  14.0      2    183.4     292.3    2019-02-24 13:15:00
            file2.wav 0           2.2   3.1      2    148.8     286.6    2019-02-24 13:30:00
                      1           5.8   6.8      2    156.6     278.3    2019-02-24 13:30:00
                      2           9.0  13.0      1    178.2     304.5    2019-02-24 13:30:00

    
    """
    if res == False and verbose == True:
        print(message)            

    return res