import click


def seqs_prior_alignment_callback(ctx, param, value):
    """Pre-process -p/--seqs-prior-alignment input"""
    alignment_format = ctx.params['alignment_format']
    if alignment_format in ('PAF', ):
        if not value:
            raise click.BadOptionUsage(
                param,
                '-p/--seqs-prior-alignment must provided '
                'for alignment format {!r}'
                .format(alignment_format))
        return value
    elif value:
        click.echo(
            'Warning: ignore -p/--seqs-prior-alignment for '
            'alignment format {!r}'
            .format(alignment_format), err=True)
        return