class ChunkyPNG::Canvas

def assert_width!(vector_length)

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