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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Make a PMF of <tt>numkdhh</tt>, the number of children under 18 in the respondent's household.
Step1:  Display the PMF.
Step3:  Define <tt>BiasPmf</tt>.
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Python Code:
kids = resp['numkdhh']
kids
Explanation: Make a PMF of <tt>numkdhh</tt>, the number of children under 18 in the respondent's household.
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pmf = thinkstats2.Pmf(kids)
thinkplot.Pmf(pmf, label='PMF')
thinkplot.Show(xlabel='# of Children', ylabel='PMF')
Explanation: Display the PMF.
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def BiasPmf(pmf, label=''):
    Returns the Pmf with oversampling proportional to value.
    If pmf is the distribution of true values, the result is the
    distribution that would be seen if values are oversampled in
    proportion to their values; for example, if you ask students
    how big their classes are, large classes are oversampled in
    proportion to their size.
    Args:
      pmf: Pmf object.
      label: string label for the new Pmf.
     Returns:
       Pmf object
    
    new_pmf = pmf.Copy(label=label)
    for x, p in pmf.Items():
        new_pmf.Mult(x, x)
        
    new_pmf.Normalize()
    return new_pmf
Explanation: Define <tt>BiasPmf</tt>.
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