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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 replace_nulls(hdrs):
 """Replace '' in hdrs."""

        ret = []
        idx = 0
        for hdr in hdrs:
            if hdr == '':
                ret.append("no_hdr{}".format(idx))
            else:
                ret.append(hdr)
        return ret