code: function tokenize() {
  
          var ch = walker.ch;
      
          if (ch === " " || ch === "\t") {
              return white();
          }
  
          if (ch === '/') {
              return comment();
          } 
  
          if (ch === '"' || ch === "'") {
              return str();
          }
          
          if (ch === '(') {
              return brace();
          }
      
          if (ch === '-' || ch === '.' || isDigit(ch)) { // tricky - char: minus (-1px) or dash (-moz-stuff)
              return num();
          }
      
          if (isNameChar(ch)) {
              return identifier();
          }
  
          if (isOp(ch)) {
              return op();
          }
          
          if (ch === "\n") {
              tokener("line");
              walker.nextChar();
              return;
          }
          
          throw error("Unrecognized character");
      }
docs: call the appropriate handler based on the first character in a token suspect