code: function kepler (m, ecc) {
    const epsilon = 1e-6
  
    m = torad(m)
    let e = m
    while (1) {
      const delta = e - ecc * Math.sin(e) - m
      e -= delta / (1.0 - ecc * Math.cos(e))
  
      if (Math.abs(delta) <= epsilon) {
        break
      }
    }
  
    return e
  }
docs: Solve the equation of Kepler.