code: function isValidDelim(state, pos) {
  	var prevChar, nextChar,
  		max = state.posMax,
  		can_open = true,
  		can_close = true;
  
  	prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1;
  	nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1;
  
  	// Check non-whitespace conditions for opening and closing, and
  	// check that closing delimeter isn't followed by a number
  	if (prevChar === 0x20/* " " */ || prevChar === 0x09/* \t */ ||
  			(nextChar >= 0x30/* "0" */ && nextChar <= 0x39/* "9" */)) {
  		can_close = false;
  	}
  	if (nextChar === 0x20/* " " */ || nextChar === 0x09/* \t */) {
  		can_open = false;
  	}
  
  	return {
  		can_open: can_open,
  		can_close: can_close
  	};
  }
docs: Test if potential opening or closing delimieter Assumes that there is a "$" at state.src[pos]