prop_startPtIsCorrect :: DottedLine -> Bool
prop_startPtIsCorrect (DottedLine start end seg ((point,_):_)) = 
  point == start
prop_startPtIsCorrect :: DottedLine -> Bool
prop_startPtIsCorrect (DottedLine start end seg ((point,_):_)) = 
  point == start
prop_startPtIsCorrect (DottedLine start end seg ((point,_):_)) = 
  point == start