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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 _get_chart_info(df, vtype, cat, prep, callers):
 """Retrieve values for a specific variant type, category and prep method. """

    maxval_raw = max(list(df["value.floor"]))
    curdf = df[(df["variant.type"] == vtype) & (df["category"] == cat)
               & (df["bamprep"] == prep)]
    vals = []
    labels = []
    for c in callers:
        row = curdf[df["caller"] == c]
        if len(row) > 0:
            vals.append(list(row["value.floor"])[0])
            labels.append(list(row["value"])[0])
        else:
            vals.append(1)
            labels.append("")
    return vals, labels, maxval_raw