def MakePoissonPmf(lam, high, step=<NUM_LIT:1>):
pmf = Pmf()<EOL>for k in xrange(<NUM_LIT:0>, high + <NUM_LIT:1>, step):<EOL><INDENT>p = EvalPoissonPmf(k, lam)<EOL>pmf.Set(k, p)<EOL><DEDENT>pmf.Normalize()<EOL>return pmf<EOL>
Makes a PMF discrete approx to a Poisson distribution.

    lam: parameter lambda in events per unit time
    high: upper bound of the Pmf

    returns: normalized Pmf