/** Returns the position of the i-th c
* @return (uint)-1 if i=0, len if i exceeds the number of cs */
virtual uint select(uint c, uint i)=0;
/** Returns the i-th element */
virtual uint access(uint i)=0;
/** Returns the position of the i-th c
* @return (uint)-1 if i=0, len if i exceeds the number of cs */
virtual uint select(uint c, uint i)=0;
/** Returns the i-th element */
virtual uint access(uint i)=0;