rotateLParser :: Parser Instruction
rotateLParser =  string "rotate left " *> (RotateL <$> int <* (string "step" <* skipOptional (char 's')))
rotateLParser :: Parser Instruction
rotateLParser =  string "rotate left " *> (RotateL <$> int <* (string "step" <* skipOptional (char 's')))
rotateLParser =  string "rotate left " *> (RotateL <$> int <* (string "step" <* skipOptional (char 's')))