code: def length_curve(obj):
      
      if not isinstance(obj, abstract.Curve):
          raise GeomdlException("Input shape must be an instance of abstract.Curve class")
  
      length = 0.0
      evalpts = obj.evalpts
      num_evalpts = len(obj.evalpts)
      for idx in range(num_evalpts - 1):
          length += linalg.point_distance(evalpts[idx], evalpts[idx + 1])
      return length
docs: Computes the approximate length of the parametric curve.
  
      Uses the following equation to compute the approximate length:
  
      .. math::
  
          \\sum_{i=0}^{n-1} \\sqrt{P_{i + 1}^2-P_{i}^2}
  
      where :math:`n` is number of evaluated curve points and :math:`P` is the n-dimensional point.
  
      :param obj: input curve
      :type obj: abstract.Curve
      :return: length
      :rtype: float