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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 _rlFindStart(rl,lz,pot,lower=False):
 """find a starting interval for rl"""

    rtry= 2.*rl
    while (2.*lower-1.)*_rlfunc(rtry,lz,pot) > 0.:
        if lower:
            rtry/= 2.
        else:
            rtry*= 2.
    return rtry