def permutationFilter(perm):
<EOL>return True<EOL>
This function can be used to selectively filter out specific permutation
    combinations. It is called by RunPermutations for every possible permutation
    of the variables in the permutations dict. It should return True for valid a
    combination of permutation values and False for an invalid one.

    Parameters:
    ---------------------------------------------------------
    perm: dict of one possible combination of name:value
          pairs chosen from permutations.