code: def position_after_whitespace(self, body: str, start_position: int) -> int:
          
          body_length = len(body)
          position = start_position
          while position < body_length:
              char = body[position]
              if char in " \t,\ufeff":
                  position += 1
              elif char == "\n":
                  position += 1
                  self.line += 1
                  self.line_start = position
              elif char == "\r":
                  if body[position + 1 : position + 2] == "\n":
                      position += 2
                  else:
                      position += 1
                  self.line += 1
                  self.line_start = position
              else:
                  break
          return position
docs: Go to next position after a whitespace.
  
          Reads from body starting at start_position until it finds a non-whitespace
          character, then returns the position of that character for lexing.