code: def _implicit_convert(cls, arg):
          
  
          # ints, long and floats mix freely with BigFloats, and are
          # converted exactly.
          if isinstance(arg, six.integer_types) or isinstance(arg, float):
              return cls.exact(arg)
          elif isinstance(arg, BigFloat):
              return arg
          else:
              raise TypeError("Unable to convert argument %s of type %s "
                              "to BigFloat" % (arg, type(arg)))
docs: Implicit conversion used for binary operations, comparisons,
          functions, etc.  Return value should be an instance of
          BigFloat.