class ChunkyPNG::Canvas

def assert_height!(vector_length)

height.
Throws an exception if the vector_length does not match this canvas' 
def assert_height!(vector_length)
  if height != vector_length
    raise ChunkyPNG::ExpectationFailed,
      "The length of the vector (#{vector_length}) does not match the canvas height (#{height})!"
  end
  true
end