code: def meco_velocity(m1, m2, chi1, chi2):
      
      _, energy2, energy3, energy4, energy5, energy6 = \
          _energy_coeffs(m1, m2, chi1, chi2)
      def eprime(v):
          return 2. + v * v * (4.*energy2 + v * (5.*energy3 \
                  + v * (6.*energy4
                  + v * (7.*energy5 + 8.*energy6 * v))))
      return bisect(eprime, 0.05, 1.0)
docs: Returns the velocity of the minimum energy cutoff for 3.5pN (2.5pN spin)
  
      Parameters
      ----------
      m1 : float
          First component mass in solar masses
      m2 : float
          Second component mass in solar masses
      chi1 : float
          First component dimensionless spin S_1/m_1^2 projected onto L
      chi2 : float
          Second component dimensionless spin S_2/m_2^2 projected onto L
  
      Returns
      -------
      v : float
          Velocity (dimensionless)