code: public final VariableNumMap removeAll(int ... variableNums) {
      if (variableNums.length == 0) {
        return this;
      }
  
      int[] newNums = new int[nums.length];
      String[] newNames = new String[nums.length];
      Variable[] newVars = new Variable[nums.length];
      int numFilled = 0;
      for (int i = 0; i < newNums.length; i++) {
        if (!Ints.contains(variableNums, nums[i])) {
          newNums[numFilled] = nums[i];
          newNames[numFilled] = names[i];
          newVars[numFilled] = vars[i];
          numFilled++;
        }
      }
      return VariableNumMap.fromSortedArrays(newNums, newNames, newVars, numFilled);
    }
docs: Returns a copy of this map with every variable in
  {@code variableNums} removed.
  
  @param variableNums
  @return