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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 _maybe_add_callable(data, out):
 """Add callable and depth regions to output folder. """

    callable_bed = dd.get_sample_callable(data)
    if callable_bed:
        out.append({"path": callable_bed, "type": "bed", "ext": "callable"})
    perbase_bed = tz.get_in(["depth", "variant_regions", "per_base"], data)
    if perbase_bed:
        out.append({"path": perbase_bed, "type": "bed.gz", "ext": "depth-per-base"})
    return out