code: def convert_base(arg, from_base, to_base):
      
      return ops.BaseConvert(arg, from_base, to_base).to_expr()
docs: Convert number (as integer or string) from one base to another
  
      Parameters
      ----------
      arg : string or integer
      from_base : integer
      to_base : integer
  
      Returns
      -------
      converted : string