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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 prepare_gold(ctx, annotations, gout):
 """Prepare bc-evaluate gold file from annotations supplied by CHEMDNER."""

    click.echo('chemdataextractor.chemdner.prepare_gold')
    for line in annotations:
        pmid, ta, start, end, text, category = line.strip().split('\t')
        gout.write('%s\t%s:%s:%s\n' % (pmid, ta, start, end))