def getNameByPosition(self, idx):
        """Return field name by its position in fields set.

        Parameters
        ----------
        idx: :py:class:`idx`
            Field index

        Returns
        -------
        : :py:class:`str`
            Field name

        Raises
        ------
        ~pyasn1.error.PyAsn1Error
            If given field name is not present in callee *NamedTypes*
        """
        try:
            return self.__namedTypes[idx].name

        except IndexError:
            raise error.PyAsn1Error('Type position out of range')
Return field name by its position in fields set.

        Parameters
        ----------
        idx: :py:class:`idx`
            Field index

        Returns
        -------
        : :py:class:`str`
            Field name

        Raises
        ------
        ~pyasn1.error.PyAsn1Error
            If given field name is not present in callee *NamedTypes*
        
stackoverflow/venv/lib/python3.6/site-packages/pyasn1/type/namedtype.py