code: public Formula binaryOperator(final FType type, final Formula left, final Formula right) {
      switch (type) {
        case IMPL:
          return this.implication(left, right);
        case EQUIV:
          return this.equivalence(left, right);
        default:
          throw new IllegalArgumentException("Cannot create a binary formula with operator: " + type);
      }
    }
docs: Creates a new binary operator with a given type and two operands.
  @param type  the type of the formula
  @param left  the left-hand side operand
  @param right the right-hand side operand
  @return the newly generated formula
  @throws IllegalArgumentException if a wrong formula type is passed