def format_repeat(protein_id, repeats):
    """Format repeats nicely for printing.

        Protein_ID    Repeat1
                      Repeat2
                      Repeat3
    """
    margin = len(protein_id) + 4
    output = ''
    for i, repeat in enumerate(repeats):
        if i == 0:
            output = f'{protein_id}    {repeat}\n'
        else:
            space = ' ' * margin
            output += f'{space}{repeat}\n'
    return output