code: public static TableFactor logPointDistribution(VariableNumMap vars, Assignment assignment) {
      DenseTensorBuilder builder = new DenseTensorBuilder(vars.getVariableNumsArray(),
          vars.getVariableSizes(), Double.NEGATIVE_INFINITY);
      builder.put(vars.assignmentToIntArray(assignment), 0.0);
      return new TableFactor(vars, new LogSpaceTensorAdapter(builder.build()));
    }
docs: Gets a {@code TableFactor} over {@code vars} which assigns unit weight to
  {@code assignment} and 0 to all other assignments. Requires
  {@code assignment} to contain all of {@code vars}. The weights in the
  returned factor are represented in logspace.
  
  @param vars
  @param assignment
  @return