       exponentiate_last: ExponentiateLast
       append_multiplication: AppendMultiplication
       append_addition: AppendAddition
+      append_equals: AppendEquals
       append_subtraction: AppendSubtraction
       negate_last: Negation
       open_sub_expression: OpenSubExpression

      with: (operator)->
        last = @expression.last()
        if last && last.isOperator()
          @expression.replaceLast(operator)
        else
          @expression.append(operator)
    class_mixer(_OverrideIfOperatorOrAppend)

          new_last = last.concatenate(@val)
          expression.replaceLast(new_last)
        else if (last && last instanceof comps.exponentiation) or (last && !last.isOperator())
          expression.append(comps.multiplication.build()).
            append(number_with_this_val)
        else
          expression.append(number_with_this_val)

