fn parse_union_type_extension(&mut self) -> ParseResult<UnionTypeExtension> {
        // `extend union` was parsed before
        let name = self.parse_identifier()?;
        let directives = self.parse_constant_directives()?;
        let members = self.parse_union_member_types()?;
        Ok(UnionTypeExtension {
            name,
            directives,
            members,
        })
    }
/**
     * UnionTypeExtension :
     *   - extend union Name Directives? UnionMemberTypes
     *   - extend union Name Directives
     */
UnionTypeExtension :
- extend union Name Directives. UnionMemberTypes
- extend union Name Directives
UnionTypeExtension : - extend union Name Directives . UnionMemberTypes - extend union Name Directives
fn parse_union_type_extension(&mut self) -> ParseResult<UnionTypeExtension> {
        // `extend union` was parsed before
        let name = self.parse_identifier()?;
        let directives = self.parse_constant_directives()?;
        let members = self.parse_union_member_types()?;
        Ok(UnionTypeExtension {
            name,
            directives,
            members,
        })
    }
fn parse_union_type_extension ( & mut self ) -> ParseResult < UnionTypeExtension > { // `extend union` was parsed before let name = self . parse_identifier ( ) ? ; let directives = self . parse_constant_directives ( ) ? ; let members = self . parse_union_member_types ( ) ? ; Ok ( UnionTypeExtension { name , directives , members , } ) }
UnionTypeExtension :
   - extend union Name Directives?
UnionTypeExtension : - extend union Name Directives?
&mut self
&mut self