[boost] [string algo] trim() requirements to high

Hi Pavol, It seems to me that trim() and its variants that currently take a Sequence argument can be made to work iterator ranges too. For example: boost::sub_range<std::string> foo = ...; trim_left( foo ); The requirement would be trim_left: forward range trim_right: bidirectional range trim: bidirectional range Am I missing something? -Thorsten