class_docstr: Abstract base class for all pathway classes to inherit from.
  
  Notes
  =====
  
  Instances of this class cannot be directly instantiated by users. However,
  it can be used to created custom pathway types through subclassing.
class_docstr_tok: ["Abstract","base","class","for","all","pathway","classes","to","inherit","from",".","Notes","=====","Instances","of","this","class","can","not","be","directly","instantiated","by","users",".","However",",","it","can","be","used","to","created","custom","pathway","types","through","subclassing","."]
docstr: An expression representing the pathway's length.
docstr_tok: ["An","expression","representing","the","pathway","'s","length","."]
code: def length(self):
      """An expression representing the pathway's length."""
      pass
  
imports: from abc import ABC, abstractmethod
  from sympy.core.singleton import S
  from sympy.physics.mechanics.loads import Force
  from sympy.physics.mechanics.wrapping_geometry import WrappingGeometryBase
  from sympy.physics.vector import Point, dynamicsymbols
label_desc: Use image node_id 4 for calling the PathwayBase obj's underlying member method code with example usage: obj.length() without return types