code: function (member) {
          _gpfAsserts({
              "Expected a _GpfClassDefMember": member instanceof _GpfClassDefMember,
              "Member is already assigned to a class": null === member._classDef
          });
          this._checkMemberBeforeAdd(member);
          this._members[member.getName()] = member;
          member._classDef = this;
          return this;
      }
docs: Add a member
  
  @param {_GpfClassDefMember} member Member to add
  @gpf:chainable