def getNameByPosition(self, idx):
try:<EOL><INDENT>return self.__namedTypes[idx].name<EOL><DEDENT>except IndexError:<EOL><INDENT>raise error.PyAsn1Error('<STR_LIT>')<EOL><DEDENT>
Return field name by its position in fields set.

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

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

        Raises
        ------
        : :class:`~pyasn1.error.PyAsn1Error`
            If given field name is not present in callee *NamedTypes*