SKIP SIZEOF SLITERAL
SKIP
* SKIP ( str len char -- str+i len-i )

Advance past leading characters in the specified string. 
 : SKIP     
   >R  BEGIN  DUP WHILE  OVER C@ R@ =
        WHILE  1 /STRING  REPEAT THEN
    R> DROP ;

ie.
skip leading characters c 
   : SKIP  >R BEGIN DUP OVER C@ R@ = OR WHILE 
                    1- SWAP 1- SWAP REPEAT R> DROP ;

toolbelt ordinary primitive