code: def _f_ops(op1, op2, swap=True):
      
      if is_float(op1):
          if swap:
              return op2, float(op1)
          else:
              return float(op1), op2
  
      if is_float(op2):
          return op1, float(op2)
  
      return None
docs: Receives a list with two strings (operands).
      If none of them contains integers, returns None.
      Otherwise, returns a t-uple with (op[0], op[1]),
      where op[1] is the integer one (the list is swapped)
      unless swap is False (e.g. sub and div used this
      because they're not commutative).
  
      The integer operand is always converted to int type.