code: def ilength(self, s, s_tol=ILENGTH_S_TOL, maxits=ILENGTH_MAXITS,
                  error=ILENGTH_ERROR, min_depth=ILENGTH_MIN_DEPTH):
          
          return inv_arclength(self, s, s_tol=s_tol, maxits=maxits, error=error,
                               min_depth=min_depth)
docs: Returns a float, t, such that self.length(0, t) is approximately s.
          See the inv_arclength() docstring for more details.